Big graphics rehaul

[SirLynix]

Still a big work in progress and requires cleanup, but is so much better.

• Implemented naive surface nets for natural blocks (artificial blocks stay blocky)
• Planet voxels are now scaled at 1/2
• Textures are now compressed (required since new textures are 2048²)
• Implemented an asset cooker to handle all assets
• Block library comes from a .json file
• Switched Lua runtime to LuaJIT and replaced a lot of C++ bridge by native Lua (mathematical classes for examples) - required because planet generation was taking a very long time.