This means we need to properly track the layer a clip was in. We now
keep track of the various signal IDs in a dedicated structure and
keep a ref on the layer an object is in.
http://phabricator.freedesktop.org/T88
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
g-ir-scanner includes section docs as class/interface docs if the section name is equal to the lowercase type name.
Since all the documentation is in section blocks, rename them to match the type names.
https://bugzilla.gnome.org/show_bug.cgi?id=727776
