Tilengine 2.11 released

[megamarc]

Hi,
I've pushed release 2.11.3 that fixes some important issues with previous release, related to the ability to use multiple tilesets per layer:

• Fixes wrong behaviour with not ideal cases: having unused or unordered tilesets inside the tmx file caused runtime exception
  
• Fixes palette conflicts. Now the engine supports having tilesets with different palettes in the same layer without breaking palette raster effects. Of course both cannot be used at once: as layer palette overrides tileset palette, messing with the layer palette when tilesets that have different palettes will cause color errors, but won't crash the engine