Improvements to TOV evolutions, pt 3

• fixes atmosphere freezing logic
• implements valencia1d formulation
• implements doublecartoon formulation
• fix the spherical1d implemention: previously we forgot to rescale the conservatives; the source terms were also missing extra terms from the covariant derivatives; we used the wrong Christoffels for the source term computations this formulation does not need the refvol factor; will document this properly in a followup PR where I also disentangle all formulations
• we now enforce symmetry for the state vector explicitly; we also enforce symmetry in the (singular) source terms; both seem to be needed to have stable long time evolutions (t=2000)