add test debug output
better comments on SMINPUTS entries
properly recalculate MS-bar quark masses at low-scales

SLHA-2 defines mu, md, ms to be input in the MS-bar scheme at 2 GeV.
mc is input at mc in the MS-bar scheme.  Therefore, when we write out
the SMINPUTS block, we must not use the mf at MZ, but recalculate them
at the their input scale.