StreamSource now have the option 'restart on deactivation' like MediaPlayer. This option is saved in XML (added Visitors for Stream and StreamSource). The GUI is added as sub-menu in play bar (like for MediaPlayer). Some StreamSource subclasses needed to be fixed to allow this feature (e.g. MultiFileSource).
Enable playing and seeking into a timeline on a media player that loaded an image. Timeline sets a duration (end) and is saved/loaded. Add a gstreamer imagefreeze element in the pipeline to simulate a playable stream. Distinction must be made between 'isImage' (what was loaded) and 'singleFrame' (what is in the pipeline). GUI is added and customized with menu and dialog.
Play speed slider changes the speed without changing direction (not working well). Change play direction is now in a play sub-menu (mouse over) in play bar. Video menu changed, with Timeline section
Change implementation of gst pipeline in MediaPlayer to use gstreamer playbin. This makes everything works more smoothly (including instant rate change). This also opens the possibility to allow audio mixing. Other bugfixes include set play speed rate at start, add video effects on reopen media player.
