Option to preserve case for chord symbols

Added option to disable auto-capitalization of chord symbols, so you can have any mixture of cases in your chord symbols.  The current options remain as well, so you can still have automatic handling of minor chords, bass notes, etc.

The option is implemented using a checkable group box.  By default, the group box is checked, meaning automatic capitalization is performed, and the options within the box control *how* this is done.  The default behavior and the behavior of all of the options within the group box should be exactly as before.  However, if you uncheck the group box, then the options within it are disabled, and your chords will render as typed with respect to case.

Here is a screen shot of the relevant portion of the style dialog:

![chord-capital-dialog](https://cloud.githubusercontent.com/assets/1799936/5477674/ae0ea538-85ea-11e4-8e57-67b188851027.png)