Features a lot of timeline-related cache optimizations as well as general
optimizations and improvements in timeline behavior. Should improve
usability significantly.
This functions more or less identically to using a media out value, but the
desired speed is preserved through block length changes, even if the block's
length is reduced to zero (i.e. no rounding errors).
An earlier commit implementing media in and out parameters was primarily for
this addition. A simple control dialog for the clip's speed presentation
reimplemented from the old codebase.
itsmattkc