Make a number of small (mostly cosmetic) tweaks:

* Pick a `[[` style
* Set up parallel tex/no-tex tests
* Move config options to the wiki
* Kill a stale comment or two
* Add `set -x` in `travis-tool.sh`
Make Dirk's suggested edits to build/check defaults.

Fixes #64.
Closes #65.
scripts to maintain parallel OS X branch
make .travis.yml work unchanged on OS X
fix check for clean working copy