Voxel rendering experiments

The data structure used for rendering is based on a 2-level brickmap of 8x8x8 voxels within 4x4x4 brick sectors, containing 64-bit occupancy bitmasks that are used for both sparse storage allocation and space-skipping. These bitmasks allow for derivation of to 3 LODs without any extra memory fetches, which enables simple and efficient space-skipping.

For more info, see: docs/VoxelNotes.md

Build requires CMake, vcpkg, and either Clang or GCC. clang-cl shipped with VS should also work.