Add loop_type and repeat_count fields to GstTocEntry plus setters and getters.
This allows to represent edit-lists in a toc as well as loops in instruemnts (wav, xi).
API: gst_toc_entry_set_loop
API: gst_toc_entry_get_loop
This is because we need to be able to signal different TOCs
to downstream elements such as muxers and the application,
and because we need to send both types as events (because
the sink should post the TOC messages for the app in the
end, just like tag messages are now posted by the sinks),
and hence need to make TOC events multi-sticky.
https://bugzilla.gnome.org/show_bug.cgi?id=678742
