Blender Git Loki

Bugs #4488 and #4431

Sequencer:
Removing feature that allowed live updates of render progress while using
scene strips. In 2.41 and older this also happens invisible, and ESC from
it works now anyway.

Two reasons:
- it is quite annoying, especially on quit renders
- new 'render to window' conflicts too much with the sequencer window
option that shows previews (in code as well as functional!)