improved measure copying routines in rntxt

git-svn-id: http://music21.googlecode.com/svn/trunk@3348 5c16147e-a200-11de-b0cc-ab0ad15e60d0
added NC as possibility in RomanText

git-svn-id: http://music21.googlecode.com/svn/trunk@3349 5c16147e-a200-11de-b0cc-ab0ad15e60d0