This is implemented on top of a Tree that represents the whole timeline.
SourceClips can not fully overlap anymore and the tests have been
updated to take that into account. Some new tests were added to verify
that behaviour in greater details
Each timeline element is in a layer (potentially spanning
over several), it is very often useful to retrieve an element
layer priority (from an app perspective more than the element
priority itself as that is a bit of an implementation detail
in the end).
Port tests to it
GstDiscoverer objects were leaked by tests making the leaks detector
unusable.
Introduce ges_deinit(), similiar to gst_deinit(), doing some cleanup
before exiting the process.
https://bugzilla.gnome.org/show_bug.cgi?id=776805
They were not serialized until now.
That implies several changes:
* Override GESTimelineElement [start, inpoint, duration] properties in
GESGroup to ensure that those properties are not serialized as they
should not be.
* Rename GESBaseXmlContainer->clips field to
GESBaseXmlContainer->containers as the hashtable now contains Groups
https://bugzilla.gnome.org/show_bug.cgi?id=709148
And fix all the tests as we need to wait for the project to be loaded
to check the reference count of the timeline (as we keep a ref on the
timeline in project to later emit "loaded" on idle).
Currently we can end up overflowing the start of others child of our
parent, avoid that making sure we can set our start to what was
requested by the user before actually doing it
+ Add a test
