Convert timeline debug feature to use the logging framework
- 'timeline' scope makes use of both of the callbacks to create a 'timeline_subscription' object for each subscription
- series ID as it is no longer necessary, because each subscription will have its own IDs
- objects will have a list 'timeline_subscription_object'.
- 'timeline_subscription_object' will be created if the object was not seen before, and checked before emitting a new object ID.
- use a
custom_writein the scope instead of adding it (the callback) in the subscriber
Adding these now to gather some feedback if the design is appropriate.
This is mostly copy-pasta with the notice that I've added a new callback in the subscriber class to allow passing va_list number of variable number of arguments. Once this was settled everything when straight in: we create a timeline type of subscriber and create a new timeline scope per compositor.