moved queue flushing out of eye process...
cosmetic work, minor improvements.
clean up of comments.
moved queue flush back into eye process, still  need a cleaner way to do this.
close device during a premature exit
Merge branch 'dev' into bilateral

Conflicts:
	pupil_src/capture/eye.py
	pupil_src/capture/main.py
	pupil_src/capture/world.py

making video capture failure exit close the device.