suzerain: add 2-arg overloads

I often just want the baseflow and not the derivatives,
so provide overloads to permit removing all of the
dontcare variable running about in a subsequent commit.

git-svn-id: https://svn.ices.utexas.edu/repos/pecos/suzerain/trunk@44915 0bd85f0b-c151-43b9-a1e9-27231104551f
suzerain: use overload to remove dontcares

git-svn-id: https://svn.ices.utexas.edu/repos/pecos/suzerain/trunk@44916 0bd85f0b-c151-43b9-a1e9-27231104551f
suzerain: adjust upper_v for spatiotemporal

Matches recent changes in apps/perfect/navier_stokes.hpp.

git-svn-id: https://svn.ices.utexas.edu/repos/pecos/suzerain/trunk@44917 0bd85f0b-c151-43b9-a1e9-27231104551f
suzerain: add FIXME re: synchronizing logic

git-svn-id: https://svn.ices.utexas.edu/repos/pecos/suzerain/trunk@44918 0bd85f0b-c151-43b9-a1e9-27231104551f