Original commit message from CVS:
* docs/design/draft-push-pull.txt:
* docs/design/draft-query.txt:
* gst/base/gstbasesrc.c: (gst_basesrc_get_range_unlocked),
(gst_basesrc_start):
Added draft for new query API.
Added draft for better selecting scheduling methods.
Make basesrc ignore length if the subclass does not support
it.