Add mouse support to the menus.

This is a terrible hack, but it gets the job done.
Merge branch 'master' into level-group
Remove Farseer project from solution, replacing it with a single assembly in an Externals folder.
Fix a bug where the par time was always zero.
Merge pull request #104 from Jjp137/par-time-fix

Fix a bug where the par time was always zero.
Merge branch 'master' into level-group
Add Load and Save methods, and create the level list.