Texture and model optimizations.

[Darkhax]

This PR makes several optimizations to models and textures which reduce the total size of the final jar by just over 1mb. (1 038 320 bytes).

Here is a break down of the various optimizations applied.

• Removed unused and irrelevant user metadata from textures files.
• Applied Zopfli compression to texture files. This is lossless compression that does not affect quality or color of textures. It is also compatible with the PNG specification.
• Added auto json minify at build time. This removes superfluous white space and new line characters from json files when the json file is copied into the final jar. The original source copy of the file is not modified.

[AzureDoom]

Wow, thanks! I'll merge this and test it. I will most likely move these improvements over to the 1.14.4 branch as well.