layout -> namedTuples
Merge branch 'master' of https://github.com/cuthbertLab/music21
Feature (chord): new chord types

Added new methods to identify chord types: major and minor sevenths, incomplete sevenths (for all recognized seventh chord types), sus4, and add9.
Update (figured bass): chord types

Redirected some code to make use of the new chord types identified in the previous commit.

Note: this edit trades ease of reading for speed, as the new chord type identification methods involve more steps than the explicit checks before.
Bug fix (figured bass): authentic cadence method

The resolution chord's quality is given by its third's quality; this can be expressed either as 'M3'/'m3' or 'major'/'minor' (respectively).
Cleanup (figured bass): authentic cadence method

Just matching the style in the previous commit. Having some coding consistency is nice.