Allow predefined cinematic camera movements (or fixed camera mode)

Change it as follows:

[ ] only people with a priv can create the animations
[ ] anyone can play the animations
[ ] Add an option (off by default unless moving is required implicitly by camera movement) to ensure player is returned to previous positions if the cinematic sequence actually moves the player
[ ] allow adding subtitles
- [ ] set start time to an earlier time calculated based on #of characters
- [ ] two modes: preserve text in a list, or erase at end time (set end time to time it was entered--which requires the previous feature "set start time to an earlier time")
[ ] fixed camera
[ ] point to point movement
[ ] add a separate camera modes for rotation: free (target moves with camera) and target (static target unless target_object is non-nil)

Poikilos / EnlivenMinetest