Another big checkin.

Another big checkin.

This includes some significant cleanups to the new course categories
system.  The basic idea is that the categories/course browser is now
unified under one system, and admin features related to that have
all been moved into the browser (as little icons).

I'm much happier with this as a foundation that can scale and be
built upon.

Still to go:

  - searching
  - paging
  - polishing

Also in here are a lot of little cleanups around the place, such as
the initial setup process.