Made the new test runner more robust and consolidated tests

[delbonis]

So now we control running the tests more from the tests.txt file, which lets us have multiple tests per file. So now we have things like pushclose:run_test_forward and pushclose:run_test_reverse from the same file. Also we don't have to individually import tests at the top and add the important bits to an array by hand.

The script parses lines in tests.txt like this:

<name> <lit nodes> [<function name>]
foobar 2
barfoo 3 run_test_baz

The last argument is optional, and it just runs run_test by default if not provided.