Since 88c02bf826 FFmpeg handles are freed if image is not displayed.
This change did not work correctly if strips are inside meta strip,
because overlap did not consider meta strip boundary, only strips inside
of meta strip.
Pass frame range to `sequencer_all_free_anim_ibufs`, if strip is inside
of meta strip, frame range is reduced to fit meta strip boundary, but if
meta strip is being edited, range must be set to +/-`MAXFRAME`,
otherwise playback performance would be too bad.
Some RNA properties and operators did not invalidate cache or did it
incorrectly.
Reviewed By: sergey
Differential Revision: https://developer.blender.org/D13101
This value was meant to be used for keeping images that are slowest to
render in cache. Method of measurement was flawed, because it doesn't
take UI overhead into consideration.
Cache panel is to be removed because users should not have to tweak
settings like this. It is not useful for development either, therefore
it is removed completely.
