hqx upscaling impactjs

Mutant Zombie Monsters Upscaled Using hqx Pixel Scaling

I finally decided that Mutant Zombie Monsters at 320 x 240 pixels is just too small, so instead of redoing the artwork and sprites which would take a very long time, I implemented hqx upscaling to the game. This upscaling method has been used on some other ImpactJS games instead of neighest neighbor upscaling because things tend to come out smoother and not as "boxy". hqx was originally developed for the ZNES emulator in C but is now ported to JS.