Cleanup

I'm working on adding a predelete hook to rsnapshot, primarily to make a tarsnap remote encrypted mirror of a subset of my backups easier.  In the meantime, I did some cleanup.  Please take as many or as few of these commits as you like, though I'd prefer you took at least through 2aea3aa.

Let me know if you'd like anything changed, removed, rearranged/rebased, etc.  I'm not an expert Perl programmer, but I was careful (and spot-tested), and I'm pretty sure I didn't make any functional changes for the worse.