Add "set -ex" to test harnesses

Luckily these weren't actually failing, but this actually goes ahead
and makes sure that no commands fail while running the tests.
Add a simple pbashc test

This doesn't really test a whole lot, simply that pbashc actually
opens and copies a file over.
Fix pbashc for #include files in CWD

I was calculating my directory stack incorrectly and therefor was
sometimes trying to read from '/'.  This fixes the bug in pbashc (and
pperlc) as well as adding a test case that explicitly checks for it.