changed the function of inversion(int) in chord to now be a way of transposing a chord into a given inversion. Added additional options for StreamIterator

git-svn-id: http://music21.googlecode.com/svn/trunk@3554 5c16147e-a200-11de-b0cc-ab0ad15e60d0
add demos and tests to StreamIterator

git-svn-id: http://music21.googlecode.com/svn/trunk@3555 5c16147e-a200-11de-b0cc-ab0ad15e60d0
remove hupomixolydian

git-svn-id: http://music21.googlecode.com/svn/trunk@3556 5c16147e-a200-11de-b0cc-ab0ad15e60d0