Pages, ExternalURLs, Assignments, Subheaders

Got a bunch of things working, more or less — lots of mop-up to do with fine details.

What's working:

- Pages (still need to process Bb MIME types to get all information and upload attached files).
- ExternalURLS (so long as they don't have descriptive text — if they do, they're Pages and are part of the MIME type issue).
- SubHeaders (with items indented underneath them recursively, to accommodate nested folders clearly).
- Assignments (need to get points, due dates, etc. out of the gradebook res00000 file).

Lots and lots of CSS fiddling while I was thinking about other things.

A redesign of the parser structure to better use Xpaths and to simplify recursion to generate indents.

General code cleanup across the board (again, while I was thing about other things).

Added some documentation about my invisible-to-Git authentication file, just for giggles (while I was thinking about other things).

Signed-off-by: Seth Battis <SethBattis@stmarksschool.org>