Add support for custom block models

[leMaik]

This PR adds support for custom block models. It can (and currently is hard-coded to do so) also replace Chunky's built-in models by models generated from the minecraft jar file.

Caveats:

• Does not support tint colors (yet, we'll have to change the way Chunky handles tint colors)
• Redstone and some other blocks are not rendered
• Redstone tinting isn't supported yet
• Water is not yet rendered and might show question marks
• Lava might be broken
• Randomized block variants always use the first block variant
• Doesn't support resource pack directories (unzipped resource packs) yet
• Azalea leaves somehow are not transparent
• Entity blocks don't show up due to entityLoadingPreferences causing them not to load by default
• You need to manually re-apply the resourcepacks once after launch (and then reload the world to update the map view)
• Replace TintedQuad and use the tints array instead (as in hard-coded models)
• JsonModel and MultipartJsonModel shouldn't be Blocks
• Fix eg. minecraft:pitcher_plant

To get the latest build of this PR, follow this guide: https://github.com/leMaik/chunky-pr-as-update-site
Due to a bug, you currently have to open the resource pack dialog and apply the resourcepacks after launching this Chunky build. Then it will load the models. Reload the world if you only see purple blocks.

Fixes #88 and fixes #426.

[jackjt8]

Outside of models larger than a block and cube-like models not rendering:

It does appear that everything else shows up to some extent. Not so much the right model, but the vanilla ones.

Otherwise, loading the whole of Greenfield indicates that there is an issue that slows down the loading of the BVH and spams the debug console with a lot of stuff.

chunky_log.txt

[Zhou-Shilin]

What's the progress?

[leMaik]

@Zhou-Shilin Needs a rebase and is not ready yet. There is a checklist above.