deps: Update stb to latest
fs: Fix memory leaks in folder watcher
voxel: Minor brush improvement
Add LOD testing mode to chunked world
deps: Update glfw (faster startup, cursor fixes)
voxel: Reorganize mesher implementation

Use functions instead of an interface, return IndexedMesh<V>, minor usage cleanup
voxel: Remove marching cubes mesher

Surface nets is stable enough to not need MC anymore
voxel: Restore soft/hard normal generation

It needs a revamp but let's keep the working code in for now
voxel: Split geometry into common and graphics

Mesher only generates common geometry; after that we generate graphics geometry as a separate pass.
This allows us to have welded vertices in the common geometry and duplicate vertices for rendering.
voxel: Generate one vertex for every grid point

We'll still need to duplicate vertices during normal generation, but that can happen in a separate step.
Fix LOD test mode and add timings
voxel: Minor cleanup