[Csync2] synchronizing file deletions

[Michael Johnson]

While investigating this, I have found that my changes to include.sh
introduced a variety of bugs, and fixing those bugs has demonstrated
bugs in parts of my hub-and-spoke tests that previously "worked".

There's nothing like writing test cases to gain a better understanding
of a piece of software!

I'm not sure that fixing those problems will resolve the deletion
propagation issues, but there's no point in investigating until I
have tests that I believe really do run correctly otherwise.