Added more model layer.

Started working on notations in particular.
Fleshing out notations a bit more.
More progress on notations.
Progress on notations. (Broken)
Notations should be mostly functional now.

Need to fix some problems in CLKit since updating to Xcode 6.1 beta 3
to test.
Fixed notation issues and added documentation.
Added placeholder methods for computed notations.
Added placeholder blocks for notation blockers.
TBNotationContainer now uses CLModelDictionary.
More progress on models.

Decided to make TBPitch a struct rather than an enum, and a TBNote is
just a wrapper around a pitch.