Add LDtk collision support

I noticed that there is no support for ldtk collisions. this would not be hard to do, because ldtk has enums, which seem to work the same as in tiled. Also, in my opinion, ldtk is better for this anyway, because it is more intuitive, easier to use, and is constantly getting updated, whereas tiled looks straight of the early 2000s.

While I love LDTK and it is my primary tilemap tool, this is not how Tiled Collisions nor the TileMapMask object are handled. There is a collision mask drawing tool in Tiled that has to be done for each tile. There is no equivalent currently for LDTK. Those drawn masks are required for the Collision Map Mask.

i was thinking that would work, but now that you point out the collision drawing tool, i guess it doesnt work. oh well