Update voxel-engine: update artpacks: add static foliage colorization

deathcap/voxel-engine@3a424083eff5b25255e283b4fb59c5b31ab24355 Update artpacks - add static foliage colorization

Commit message generated by https://github.com/deathcap/lmno-cl

Ref https://github.com/deathcap/artpacks/issues/8
Uses https://github.com/deathcap/graycolorize - see for example
of how this improves MC texture pack compatibility, e.g. with
https://github.com/smenes/Faithful32