Improve sorting in the track tables BPM Options submenu

Sort by the most used options and add some separators for clarity.
Also rename the submenu from BPM Settings > BPM Options. IMO this is
the more correct term since the menu contains the available options for
the BPM setting of a track.
![mixxx](https://f.cloud.github.com/assets/4525897/658294/8fddd540-d5d1-11e2-9208-84d929e6b0ae.png)

PS. A test to see how forks and pull request work. New to this.