Animation notes

[ABX]

1. Seems samples/animate/anitest.rc can be removed because new sample correctly
reuses ../sample.rc

2. Can anyone familar with distribution, take care for making samples/animate to
be present in _any_ of the files in distrib? (I wonder if there is any other new
sample which requires adding to distribution)

3. I think I saw .Ok() in one of generic animation code. Could be nice if we
could follow new .IsOk() interface in new code. Sorry if that's not the case.

ABX