Drop shadows on no collision/air tiles

[amykatname]

I'd happily code it and make a pull request...If I knew how to
The drop shadow feature still applies to non-solid tiles, which I feel like it really shouldn't
Also kinda similar to #39 but I feel like straight up disabling shadows on tiles with no collision is a way simpler fix
Even though this might be seen as subjective it's clearly an issue if you go in a vanilla water level with it on, as the water at the top is just non-solid tiles, which as you can see... not good

[qixils]

I'm pretty sure some people will want non-solid blocks to have shadows, so #39 would be the more likely solution here IMO, especially as the hard part is actually filtering out tiles, not the process of deciding what should be filtered out