This commit amends Cheb_2dmg::resid_dot (dot-product of
residual vectors in the context of the 2D GMRES/multigrid
iteration) to perform the dot-product in the simplest way,
as a sum over grid elements.

Before this, the code (which is left in the file but
disabled by #if 1 / #else) tried to be clever and
evenly-weight contributions from the interior, the boundary
conditions, and the mean-pressure error (if the problem was
indeterminate).  This evidently caused the long-standing
problem of the GMRES inner iteration being far more
optimistic about error (as reported by LAPACK) than would be
computed by directly measuring the residual error.

This problem was ultimately discovered when the
doc_map_iwave case broke.  Even though this broken residual
code has been in SPINS since before it was
version-controlled via GIT, the map_iwave case would still
converge (and relatively quickly) when the multigrid
iteration had a relatively large coarse-solve size.

Git bisect pinned the broken documentation case on the
change that reduced the coase-grid size, which reduced the
GMRES convergence rates enough that the errors caused by
*this* problem broke convergence.

Since this change replaces the error norm calculations used
by GMRES, it should be treated with caution and mapped-grid
cases should have a mark-1-eyeball inspection of results for
a while.

--

Additionally, for debugging utility this change also
includes crude residual/basis output for the 2D GMRES
solver.  All current uses are commented out.