Create LevelGroup.cs.
Merge branch 'master' into level-group
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.
Remove unused using statements and commit the .contentproj file.
Implement resource path switching depending on Debug or Release configuration.
Don't hardcode the file name in Save().
Merge remote-tracking branch 'jorenz/level-group'
Fix setup path.
Make UserDataPath more cross-platform compatible.
Pass the level's name around everywhere.
Make the Next Level button work.

The FullPath property and the FindNextLevel() method was added
to LevelGroup in order to make this easier. Much of the
functionality itself is in CompletionScreen.

- Michael and Jorenz