Do not simplify the threshold corrections, to make the result more
readable.  (Simplify[] does not really do any simplification, the
result just looks more complicated.)
Add test for the MSSM low-scale constraint
generalize gauge cougling getter function in the tests
Include the other gauge couplings in the threshold corrections test
routine.  However, the final test does not include them, because
we don't have corrections to sin(ThetaW) now.