FlxG.switchState: added conditional check for flixel_addons that handles FlxTransitionStates cleanly
added FillStyle back to make flixel-addons compile again (needed for shapes)
Cleaned up FlxG.switchState transition a bit.
Transitions: removed FlxG.switchState hack for something a bit more elegant, added lightweight transition API to FlxState
Transitions: removed FillStyle from my branch now that it's no longer necessary
Merge pull request #1274 from larsiusprime/feature_transitions

Feature transitions