Fix Flash Prerotated animations
Call calcFrame() when setFormat() Fixes issues #619 and #620
Merge branch 'flxtext_alpha' of https://github.com/mrcdk/flixel into flxtext_alpha

* 'flxtext_alpha' of https://github.com/mrcdk/flixel:
  Call calcFrame() when setFormat() Fixes issues #619 and #620