Update FlxTypedButton.hx

Fixed `loadGraphicsUpOverDown` to use `bd` instead of `asset` - it was already going through all the trouble of getting the `BitmapData` from a string, if you passed one, and then not using that `BitmapData` afterall, and assuming you had passed one...
Merge pull request #37 from SeiferTim/patch-1

Update FlxTypedButton.hx

Good job :)