#2 Terminology change from Test to SysTest

Hi all,

This is a pull request to change the terminology of the systematics tests from Test to SysTest in order to avoid confusion with unit tests and other coding checks.  Not much involved here--just changing the class names and a few internal variables for clarity.

As we discussed briefly on the telecon, you can click on the "files changed" tab to see what I've changed in the code.  You can leave inline comments on that page if you have them, or leave a comment here with your thoughts.

One other check to do is to go into the tests/ directory and try running all the scripts included there. Those are the unit tests--they're not complete yet, but if they raise an error on your machine, that lets us know I broke something on your architecture even if the changes are OK for mine.  (The unit tests are not set up to run automatically yet--another thing to do, I suppose.)