Add local vs world flag for particle velocity

Adjust reference frame for affector to be consistent (so angles are
counted clockwise from "up" in both local and world modes).

Bug: skia:
Change-Id: I643e1484bc0a58d1f1c0cfe35ac2ab37dc2ea409
Reviewed-on: https://skia-review.googlesource.com/c/194189
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
4 files changed