Add DefineButtonTag Reader and Writer
Add writeFixed16_16 method
Update ButtonCondAction and DefineButton2Tag, add BlendModeRecord
Add BlendMode implementation
Add readDefineButtonTag and readButtonRecord2
Add readButtonCondAction method
Add TODO comment
Add writeDefineButtonTag and sub methods
Merge pull request #44 from alucas/push_definebutton2

Add DefineButtonTag and DefineButton2Tag.