My ongoing devel branch w/ rebased branches.

[chadnetzer]

Incorporates many @wolfospealain changes, and closes issue #1, #4, #5, #15, #17, #18, #20, #21, #24, #26, #27, and #28.

I did a fresh series of merge/rebases to create a less intimidating merge history, which should be easier to review as a whole than 20 separate stale PRs.

The software still works on Python 2, but now also works with Python 3, and I've tripled the number of tests (with more to come).