Speedup for skin modifier, avoid calculating normals many times
Use fill function for setting origindex
Use api function for flipping button list & rename to BLI_listbase_reverse
Fix T40800: Crash when editing material nodes

it was caused by ee5f432. Not sure why exactly blender runs into
threading conflicts here since material preview works.

Let's keep it simple for now and disable material nodes preview,
because it's not supported by the interface anyway.

This is to be included to the final release.
Fix T40776: Crash when using empty curve as a deformation target
Fix T40757: Video Texture - Video frames dropped from beginning and end

it's actually a followup for 04f81c8, no need to apply offset for video files.
Merge remote-tracking branch 'upstream/master'