MacGui: re enable deinterlaced still preview images when deinterlace is selected.
- Also add a deinterlaced preview still image when decomb is selected as libhb does not notice decomb for still previews. Do a quick shell game when decomb is selected only to grab a deinterlaced preview.
- As a side note, remove some extremely vestigial code from controller.m as far as a min preview size.
- fwiw, lingui already apparently does this.

git-svn-id: svn://svn.handbrake.fr/HandBrake/trunk@5239 b64f7644-9d1e-0410-96f1-a4d463321fa5