This should make VSE code more readable and easier to understand from an
outside perspective.
The name was chosen to be `channel` rather than `channel_index` to keep
things short and concise -- it should be clear based on the context
whether we are talking about the strip's channel index (singular case,
`Strip::channel` or `SeqTimelineChannel::index`) vs. the channel list
(plural case, e.g. `Editing::channels`).
Pull Request: https://projects.blender.org/blender/blender/pulls/138919
Rework internals of how VSE caching is done. Primarily to make all the
caching logic more understandable from development point of view, but
also has several user visible implications (more details in the PR):
- Simpler and fewer caching UI options,
- Disk cache is gone (primary reason: proxies are kinda the same thing),
- VSE cache size set in preferences is actual size used for VSE caches
now (previously caching stopped as soon as whole Blender used that
much memory, even if some memory usage was not about VSE at all),
- Certain scenarios of cache invalidation are faster now.
Pull Request: https://projects.blender.org/blender/blender/pulls/137926
