Changed VhAtMin of nmssmsoftsusy.{h,cpp} to be non-const for future use of
other non-const functions.  softpoint.x output unchanged (as it
should be).  May consider reverting back to const in future
Modified VhAtMin() of nmssmsoftsusy.{h,cpp} to take 3 vevs as arguments and
call calcDrBarPars() within the function.  It now becomes important
to call VhAtMin() in the right part of the SOFTSUSY iteration as the
call to calcDrBarPars() obviously affects subsequent display values.
To deal with this, I've moved the call to VhAtMin() to the end of rewsb,
which is also where Ben checks the Higgs potential is unbounded from
below in softsusy.{h,cpp}.  One deviation noted in the achived accuracy -
it goes from 7.80038319e-05 to 7.80043657e-05
Removed loop argument from VhAtMin() since I want this to calculate the
effective action at 2-loop order in one go.  Output unchanged.
Rewrote tree level expression for the effective potential in terms of v1 and
v2.  Found bug in original expression in term ~ a_lambda which was
missing a factor of 1/root2.  Removed loop from argument of VhAtMin()
Changed variable names cb --> cosb, cos2b --> c2b to be more consistent with
rest of conventions in SOFTSUSY code. Output unchanged.
Global min test setup at end of rewsb.  Tests 4 scenarios of vanishing vev.
flagHiggsNoMin() works as expected.