Added a test / debug mode to scripts (-z). Lets you run antsCorticalThickness in about an hour.

It also does not quit on errors, so you can debug nonfatal errors without having to
start computation over.

Mostly speeds up by doing faster registration - but also does very few thickness its.

To achieve complete reproducibility, multi-threading needs to be disabled separately.
Merge pull request #81 from stnava/pac

Added a test / debug mode to scripts (-z). Lets you run antsCorticalThic...