Remove the device path list in the constructor of Pipeline.
Fix problem with sync.

The error was gstbasesink.c:2769:gst_base_sink_is_too_late:<xvimagesink2> warning: There may be a timestamping problem, or this computer is too slow.
Use api 1.0 for Gst.Message.
Pass sys.argv to Gst.init_check().
Make pipeline a shell.
Enforce version 1.0 of Gstreamer.
Change switch_to() to the new API.

In Gstreamer1.0 the InputSelector doesn't have anymore the "switch" signal.
This can be found on commit 9c4ce4ae1682 of gstreamer.
sink%d -> sink_%d.
Remove 0.10 code.
Add comment about the 'sync=False' attribute.
Catch errors in the shell and show them.
Add shebang to pipeline.
Update code to Gtk3.
fix
Update to new APIs.
Some fixes.
Complete threading management.
Fix 'Add video source' dialog.
Remeber to initiate X11 thread.
Add emptyline().