Changed the algorithm responsible for dynamic chunk updates to be based on actual FPS, instead of estimated vsync idle time. Works more reliably.
Merge branch 'master' of github.com:fragmer/ClassiCube-Client
Introduced flexible "framerate limit" setting.

Instead of an on/off "limit" switch, there are now several FPS limits to choose from: {20, 30, 40, 60, 75, 85, 120, 144}. Any modes above user's monitor refresh rate will not be shown. Value of "0" means "no limit". The setting has been renamed from "limitFramerate" to "framerateLimit", but backwards compatibility is preserved.