Implement word access to floats
BitBlt: export as named primitive, allow zero extent
FloatArrayPlugin: implement at/atPut
Fix cloning of word/bytes objects
Add primitiveConstantFill
Throw errors not strings
Report missing primitives only once
Fake balloon 2D drawing primitives (B2DPlugin)
Add BitBlt rules 32 and 34
Add primitiveGetAttribute
Recategorize some primitives