2017-07-04-release

This is a Windows build from GCC of the commit tagged "2017-07-04-release". It has a few minor optimizations; notably, only polling 4 times per frame at the target frame rate to reduce CPU usage. It uses 0.01%-0.02% in my testing on an i7-2600K CPU. The instructions should be visible upon running the program, but in case they're not, use Alt or Numpad0 to mash the space bar 50 times per second, Z or Numpad4 to flip-walk left, C or Numpad6 to flip-walk right, and X or Numpad5 to alternate left and right arrow keys 50 times per second.