Rewrite NR 3.2 Titles and headers. (issue3667041)

[markpolesky]

Reviewers: ,

Message:
Hey guys.

Here's a complete rewrite of
NR 3.2 Titles and headers.

Please comment.  You can disregard the first couple
of patch sets, and go straight to the "First Draft"
one.

Thanks.
- Mark

Description:
Rewrite NR 3.2 Titles and headers.

Please review this at http://codereview.appspot.com/3667041/

Affected files:
  M Documentation/notation/input.itely
  M ly/titling-init.ly