Allow Calculator to be instatiated with a direct framerate value.
Import soft dependencies in try-blocks at module level.
Add a video player class.
Add subtitle and timecode overlays.
Add function to set subtitle text.
Use PT fonts and a shaded background by default.
Add a preliminary action to load video.
Merge ../gaupol into gst

Conflicts:
	TODO
Add containers for video player etc.
Implement loading video.
Merge ../gaupol into gst

Conflicts:
	TODO
Merge ../gaupol into gst
Do not try to initialize video player containers more than once.
Implement changing application window layout.
Implement showing and hiding the video player.
Implement playing and pausing video.
Implement video player seekbar.
Add video player test script.
Implement video player subtitle text overlay updates.

If someone thinks this is horribly inefficient, we can optimize it
later.
Implement seeking by subtitle and 30 second jumps.