Automatic update of common submodule

From dbedaa0 to d48bed3
ges: Add padding for API extension where missing
ges: Remove versionning infos now that we start on the 1.X API serie

They are now meaningless, all the current symbols are the basic
ones for the 1.X serie.
track-element: Remove constructors for TrackElement from the API

Most of the time the user should not create GESTrackElements
himself, instead he should add a GESAsset to a layer, that will
result in a clip creation and the proper TrackElements to be
created and added to the tracks.

The case of effects and overlays is a bit different as the user should
create the TrackElement and add them to a clip.
base-xml-formatter: Emit 'loaded' right after a project with empy timeline is loaded

https://bugzilla.gnome.org/show_bug.cgi?id=720040
.gitignore: add test driver and more test binaries
track-element: clamp interpolated keyframe values.
Automatic update of common submodule

From d48bed3 to 1a07da9
ges-asset: Do not forget to give a ref to the registry

+ Add test in the testsuite
+ Fix broken tests

https://bugzilla.gnome.org/show_bug.cgi?id=721111
videosource: Always add a deinterlace at the beining of videosrcbin

It might be needed in some cases (for example when decoding prores files) and
it is the way it is done with playbin now. Also deinterlace now properly supports
passtrough mode.
uri-asset: Let a chance for user to change URI if the set one is not readable

It sounds like the most logical thing to do in that case.

https://bugzilla.gnome.org/show_bug.cgi?id=721111
ges-pipeline: Rename add_timeline to set_timeline

API BREAKAGE:
        - ges_pipeline_add_timeline
        + ges_pipeline_set_timeline
tests:integration: Fix a race about get_position being called before AYNC_DONE happens
ges: Some documentation cleanup
ges-extractable: Return NULL instead of G_TYPE_INVALID

The return type of this function is gchar *, not GType
ges-group: Properly check for integer underflows

error: comparison of unsigned expression < 0 is always false
ges: Remove unused functions
ges: Give a reference to the formatter for the idle callback

This avoid segfault as we are not guaranteed that the formatter will
not be destroyed in the meantime.

+ Minor cleanup of handling of private members

https://bugzilla.gnome.org/show_bug.cgi?id=724337
Rename TIMELINE_MODE_XXX to GES_PIPELINE_MODE_XXX so it corresponds to reality

First, it was not in any namespace, second the name of the enum is
GESPipelineFlags.
timeline: Make sure not to add 2 times a TrackElement in the same track

Without that, if a UriClip contains several tracks of a same type (ie.
video or audio...), we would add all the TrackElements to each track
making everything failling as we end up with several GNL sources at
the same position with the same priority.