Consider a file testable if it's anywhere in phpunit-run-directory.
Save buffers when running tests.
Don't use compilation-directory, use phpunit-run-directory.
Change back to phpunit-run-directory when retesting.
Assume anything under "test/" or "tests/" is testable.
Fix retest binding.
Fix customization, there was no (defgroup) to define the 'phpunit group.
Added initial code