SkewbSkills: FLT and L2LT with stopwatch, less unnecessary stuff

Uses a more accurate stopwatch, features a stopwatch for the First Layer Trainer.
Added more buttons in the menubar, more shortcuts for settings.
Faster way in which the scrambles for the FLT have been generated, using less disk space and fewer lines of code. Loading new scrambles in the FLT will not take as long as in the previous version.
Help window containing a guide to use SkewbSkills.