Ported BmpBlender stuff from TileZed.
Use #define WORLDED to keep code in sync with TileZed.
Ported BMP stuff from TileZed (moves BmpBlender into MapComposite).
Added more robust error-checking of Rules.txt and Blends.txt.
BMPToTMX uses the new BMP-related classes.

ConversionEntry -> BmpRule
Blend -> BmpBlend
Use BmpBlendsFile and BmpRulesFile for reading.

getBlendRule() code is still duplicated between this class and BmpBlender.
BMPToTMX writes BMP-related settings to new maps.
Synched some code with TileZed.