Make 'constant_dirichlet' option work
Merge pull request #63 from grinsfem/constant_dirichlet

Make 'constant_dirichlet' option work
Move pressure pinning to side_constraint for IncompressibleNavierStokes
and LowMachNavierStokes.
Need to pin the presure on the boundary now.
Use correct header.
Move pressure pinning to side_constraint in ReactingLowMachNavierStokes
Needed to up the tolerance a little bit.