Memory deallocation bug in Drawables

[PSteinhaus]

When running the drawing example I see a problem with memory comsumption; the process crashes after a few minutes. Same behavior under Ubuntu or Centos. This seems the buggy memory allocation:

amsoares@ubuntu:drawing$ pmap -x 4964 | grep renderD128 | wc -l # <-- Value increases until it crashes
64488
amsoares@ubuntu:drawing$ pmap -x 4964 | grep renderD128 | wc -l # <-- Already crashing
48439
amsoares@ubuntu:drawing$ pmap -x 4964 | grep renderD128 | wc -l # <-- Process dead
0
amsoares@ubuntu:drawing$

I'm not a developer, I'm just learning Rust and ggez/gwg.

Originally posted by @ccie18473 in #57 (comment)

[PSteinhaus]

This is really bad.

I haven't yet had the time to look much into it, but for some reason memory leaks have started to come up in all of our examples where Meshes are created inside the draw loop and then dropped, meaning there is probably still something wrong with them not deallocating their ressources correctly.
I haven't tested yet whether Image, SpriteBatchor MeshBatch are impacted as well.

I assume it's the textures not being released correctly, due to the hacky system we currently have in place for that, but I could be wrong.

I'll try to look into it as soon as I can.

[PSteinhaus]

Fixed in cf3a50b