Tests: fix directory in use ordering issue in dir cleanup (caught by tests on windows)
Tests: add RunTests.fsx, enables test run from FSI and on windows

- In windows, this is the only way to run the tests, since running them from the compiled assembly will fail with a referencing error that I haven't figured out
- Had to fix some issues in the typescan tests to make this work.   Amusingly, typescan has to be functioning properly for this run mode to even work.