Allow no restriction caps in xml formatter
requested to merge hwilkes/gst-editing-services:allow_no_restriction_caps_in_xml_formatter into master
Allow ges_base_xml_formatter_add_track() to accept a properties that does not contain the "restriction-caps" property. If it is missing, the restriction-caps are not set.
Also check that, if "restriction-caps" is given, a non-NULL cap is actually returned by gst_cap_from_string()
Edited by Thibault Saunier