Sign error
Was using wrong g. Commenting out mass_residual part and the extra
momentum equation terms. I don't understand why yet, but these terms
do very strange things to the solution that I don't think is correct.
Sign error.
There were was a sign error in the momentum part of Boussinesq stabilization,
but it doesn't seem to matter. However, I currently cannot reconcile the behavior
of the PSPG part. The sign seems wrong to me, but if I change it from this,
energy is being sapped from the convection_cell example. The current form
gives something that looks like reasonable behavior. Need to try testing
without the PSPG terms and just do Taylor-Hood and see what happens.