New branch with some hooks for comparing non-local term
close to matching nonlocal term, still weird at top level
Getting closer to matching GHAT and GHAT2
more diagnostic output for comparing VDC*GHAT and GHAT2... values are only the same when GHAT=0, relative differences range from 1e-10 to O(1) and I don't know why (yet)
new routine to make debugging easier
more diagnostics - I think the problem is in padding denominator with 1e-10
Figured out one issue with GHAT (enhanced diffusivity), still have rel errors O(1e-4) though... next step is to track down where those large errors occur and figure out why
Verified that differences between native POP and CVMix are 1e-10 or
smaller for nonlocal term!

This commit comments out all of the diagnostic output (calls to
MNL_DEBUG), sets VDC and VVC to BLMC2, and uses GHAT2 instead of GHAT
for KPP_SRC.
Update to use latest variable name changes