e49963c6a7
Two quality-of-life additions to juggle the `Strip` and `KeyframeStrip` types: - New function `Layer.strip_add<KeyframeStrip>()` that returns a `KeyframeStrip` instead of a `Strip`. - Implicit conversion operator `operator Strip &()` on `KeyframeStrip` so that `KeyframeStrip` can be passed to a parameter of type `Strip &`. No functional changes. Pull Request: https://projects.blender.org/blender/blender/pulls/122659