Integer range

Because upper bits are twiddled when rotating tiles a standard signed int or a 16 bit int leads to errors when loading maps with rotated tiles. This is especially true when loading csv encoded data which will skip the datastream without error. I have changed the types, where I could see them as a problem to sf::Uint32 types.

I'm hoping to make a pull request later with code for recognising rotated tiles and this is a prerequisite for that. I'll do a work in progress PR for what I have if you want to discuss it to get it fitting nicely with your interface. 

Please let me know if I've done it wrong, still getting my head around the code base.

Thanks