unit tests for QSObject

Just a few basic tests to start things off. I wanted to have these in place before working on fixing #861. You'll notice that a couple of them fail, based on how I think things should work. Feel free to dispute my assumptions.

The changes I made to actually run the tests appear to apply only to the local user's environment, so they aren't in the commit. Here's what I did to run them:

  1. Edit Scheme (⌘<)
  2. Choose "Run All Tests"
  3. Choose "Test" on the left
  4. Under "Tests", add all the test-related targets (or just the ones you want to run)