Fix missing types to be 'unsigned char' not 'int'
Fix handling of string constants which are const-char-* on modern compilers

Conflicts:
	stb_voxel_render.h

Added a few missing consts to remove GCC warnings about deprecated
conversion from string constant to 'char*'

Removed unnecessary parenthetical.

clarify which config macros are required and which are optional

Request a 24-bit depth buffer

Build fix

x, y, z members not found because stbvox_default_normals contains arrays not structs.

I like the word 'implementation'

reconstruct full table of bit allocations per mode

support making all definitions static so you can have multiple copies of file (with different #ifdefs);
move all tables to end of file (this will have to be undone later because IIRC it's not compatible with C++ or with some compilers or something, but it'll make my life easier in the interim);