and update plugins cache

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CID 1461701

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CID 1463853

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We need to ensure that clips duration is set after time effects are
added and we now need to serialize effects inpoints and max duration.

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These notes cover time coordinates in GES, time effects, time
translations.

It also goes into why keyframes will not work with non-linear time
effects.

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ges_uri_clip_asset_get_duration does not tell us what the duration in
the timeline needs to be. Especially when we have time effects, or
effects with finite max-durations. So we should no longer expect the
duration to stay the same when replacing assets. Instead, we just check
that the new max-duration would be compatible with the current in-point
(which was not checked before), and the clip would not be totally
overlapped if its duration-limit changes.

This is based on the assumption that each source is replaced one-to-one
in its track. If a source is replaced with nothing in the same track,
this check may be a little too strong (but still mostly weaker than
before). However, problems could occur if track selection does
something unexpected, such as placing the new source in a track not
previously occupied.

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The out-point, which is an internal time, is used instead of the
duration for determining the control binding value at the end of the
element.

Also, allow the user to switch off the auto-clamping of control sources
if they are not desired. And allow them to clamp specific control sources
individually.

Also, fix a lot of memory leaks related to control sources. In
particular, releasing the extra ref gained by source in
g_object_get (binding, "control-source", &source, NULL);

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Make sure the layer exists before we try to remove the grouped clips
from it.

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If a layer priority sits between the priorities of two layers in the
timeline, i.e. it references a gap in the timeline's layers, then
ges_timeline_append_layer will never fill this gap and create the
desired layer, so the edit in timeline-tree would loop forever. So a
check was added to avoid this.

This would be a usage error, but a user can reasonably end up with a gap
in their layers if they remove a layer from the timeline.

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Unlike ges_container_add, this lets you set the index and will check
that track selection did not fail. This is useful for time effects whose
addition would create an unsupported timeline configuration.

Also can use the clip add error in ges_timeline_add_clip to let the user
know when adding a clip to a layer that its in-point is set larger than
the max-duration of its core children.

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When trimming the start of a clip, we want to set the in-point of its
children such that whatever data was at the timeline time T still
remains at the timeline time T after the trim, where
  T = MAX (prev_start, new_start)

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The new in-point should be the media position corresponding to the media
position. media_duration_factor is no longer needed.

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The duration-limit case was missing a 'break;' statement.

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Add methods to convert between the timeline time coordinates and the
internal time coordinates of a track element in a clip, taking time
effects into account.

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Allow the user to register a child property of a base effect as a time
property. This can be used by GES to correctly calculate the
duration-limit of a clip when it has time effects on it. The existing
ges_effect_class_register_rate_property is now used to automatically
register such time effects for rate effects.

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Added more errors to GES_ERROR for when edits fail (other than
programming or usage errors). Also promoted some GST messages if they
related to a usage error.

Also added explanation of timeline overlap rules in user docs.

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We have little control over those as they are generated by streamsynchronizer in a not reproducible way

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And fix typos.

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This was complexifying the implementation for very little gain.
Each source type should ideally have its own API.

In that patch we make it so we do not have to subclass anything
but instead use GESAsset to pass information about how the pipeline
should look like.

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Otherwise there is a pretty rare race where we get the
_initialize_stack_func executed leading to the stack set up and
the source pushing buffers before the composition source pad is
activated, and a STREAM_ERROR is reported as we end up pushing a
buffer to a flushing pad.

Thanks rr chaos mode for showing that improbable race

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While this is not correct, we can't predict from what thread a
GstElement will be disposed as it might still be referenced by
a GstMessage somewhere which is freed by, any thread.

In this specific case we can assume that GES user will already have
let go his timeline reference and we should not avoid assert in that
specific case as it should be safe to let the timeline be destroyed
at that point.

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It is the right ordering and in Pitivi we set the project size
when adding the first (relevant) asset, meaning that our code to
reposition clips would kick in (in the unit tests) if we do not respect
that ordering.

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Open up the method to the user, since they may need the information.
Also added more documentation on what a core track element is to a clip
and how they are treated.

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Prevent a few memory leaks in the tests.

Also mark ges_project_save as transfer full for the formatter asset.

Also make sure that ges_project_request_sync is transfer full on the
returned asset.

Fixes #104

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Prevent setting of properties or that of children, if the clip would not
be able to set the corresponding duration if the duration-limit would
drop below the currently set duration.

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Each active non-core child must have a corresponding active core child
in the same track. Therefore, if we de-activate a core child, we also
need to de-activate all the non-core children in the same track.
Similarly, if we activate a non-core child, we need to activate the
corresponding core child as well.

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Make less assumptions about the priority of effects and core elements so
that the code would still work if the priority of an element was set
directly. In particular, the index of a top effect will always be its
position in the effect ordering.

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GESGroup no longer uses this, and GESClip can be made simpler without
it.

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When splitting a clip, keep the auto-transition at the end of the clip
alive and move its source to that of the corresponding split track
element.

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We first change the duration of the splitted clip, then we add the new
clip to the layer and assign the tracks for its children. Normally, when
a clip is added to a layer it will have its track elements created, if
needed, and then assigned to their tracks. This will fail if any sources
would fully or triple overlap existing sources in the same track.

However, here we were adding the clip to the layer *and* avoiding the
track assignment process and instead setting the tracks explicitly. In
particular, the order was:

+ add new clip to layer with no tracks assigned
+ shrink the split clip
+ assign the tracks for the new clip

This has been changed to:

+ shrink the split clip
+ add new clip to layer with no tracks assigned
+ assign the tracks for the new clip

Thus, the order of events for any users connecting to object signals
will be close to that of adding another clip to the layer.

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Any time a track element is added to a track, we need to check whether
we need to create a new corresponding auto-transition. This simply moves
the code from ges-clip.c to ges-timeline.c, where it is more appropriate.

Moreover, it technically opens the possibility for creating
auto-transitions for track elements in the timeline that have no
corresponding clip.

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Also trim the in-point of non-core children of clips to ensure that
their content will appear in the timeline at the same position.

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