Removed commented-out code in Boolean AND shaders
Don't need to blend everything else in Boolean AND scene, just sort it
Change which pass defines intersection group in Boolean AND scene
Simplify culling when rendering intersection in Boolean AND scene
GLSL utility for finding a normal in a volume
GLSL utility for shading a normal
Boolean XOR approach samples front-to-back with shading
Boolean AND approach samples front-to-back with shading
Uniform slicing shades
Attribute slicing shades