Beginning to make things framerate-independent.
I think I've more or less got motion there, but there are a lot of things (ex. invincibility frames) that still depend on the raw frame numbers.  Also trying to figure out why, under Chromium and Firefox on Xubuntu, drawing is sort of "laggy" - it looks like you're underwater, almost like parts of the screen are drawing before others even though all the drawing happens at once.