core unit-tests cleanup

* Use atomic (i.e. self-contained) tests.
* Fix typos that caused recently-added tests to erroneously fail.
* Consistent whitespace (tabs only).
* Always use strictEqual instead of equal, to avoid false-negatives.

All tests pass right now except the SAT overlap test, which is
-13.858192987669298 instead of -18.47759.
(The test was already failing before -- I didn't change anything.)
fix leakage of global variable from forgotten "var"

fix leakage of global variable from forgotten "var" (revealed by QUnit)
fix description mistake
Merge pull request #444 from sbyrnes321/develop

Clean up core.html unit tests