add some more glsl/shader functions
add a default value for aspect ratio
start working on rendering sky color/aerial perspective stuff

just brute-force method for now, and probably need to adjust
some constants, but looks more or less reasonable
clean up some commented out junk
starting work on loader for radiance hdr image files (.pic,.hdr)
export basecode:mouse-move
fix/optimize radiance hdr image loader
update to match glop change