Diff in Testing Group XML

[rosenbrockc]

At the moment, if a code file's accompanying XML file is changed, a re-parse is triggered and the code base is considered altered, even if the code file itself didn't change. This also triggers a re-run of all the unit tests that depend on that code file.

If the only thing that changed is the unit test specification for a specific subroutine, then only that subroutine's unit tests should be re-run. We could do this by comparing the new XML contents to the old ones and then recognize what actually changed.