Modernized corpora docstrings.

git-svn-id: http://music21.googlecode.com/svn/trunk@3688 5c16147e-a200-11de-b0cc-ab0ad15e60d0
Improved corpora docstrings.

git-svn-id: http://music21.googlecode.com/svn/trunk@3689 5c16147e-a200-11de-b0cc-ab0ad15e60d0
added partial support for breve, long, maxima TS

git-svn-id: http://music21.googlecode.com/svn/trunk@3690 5c16147e-a200-11de-b0cc-ab0ad15e60d0
Fixed lyric problems for word extensions without words and corpus.search (temp fix)

git-svn-id: http://music21.googlecode.com/svn/trunk@3691 5c16147e-a200-11de-b0cc-ab0ad15e60d0