Changed from software to hardware texture tileing.

[Rinnegatamante]

Changed from software to hardware texture tileing as suggested in issue #22 .

Some note about this modification:

1. I've leaved the code for the original tile32 function since i've noticed targets got added to sf2dlib. I don't even know how they really work and i don't have much time to test them so if someone wants to add tile32_hardware support to them too, it can try it.
2. I tried to leave the code similar to the old syntax but i probably suggest to force texture->tiled = 0 in fill_texture_from_RGBA8.
3. There are probably better way to do so but this works fine and since in like 3 months anyone pulled this modification, better this then nothing i think.

[Cruel]

If you do this, I don't think you can use smaller textures. You try testing 8x8 and 16x16 textures?

You may need to change TEX_MIN_SIZE to 32 to get them working.