Release v2.14.0

Changed

• No packaged mdp uses a Berendsen thermostat or barostat any more, and every one of
  them now passes grompp with zero warnings --- which none of them did before.

• Every temperature-coupled stage now uses the V-rescale thermostat. All seven
  packaged mdps used Berendsen, which Gromacs deprecates in the same breath as the
  barostat: "does not generate the correct kinetic energy distribution." That is every
  stage htpolynet runs, including the ones that produce published densities and
  transition temperatures. Same cause as the barostat, and the same remedy; tau_t is
  unchanged at 0.1 ps.

• Constant-pressure stages no longer use the Berendsen barostat. npt.mdp,
  drag-npt.mdp and relax-npt.mdp now use C-rescale, which samples a correct NPT
  ensemble and is robust far from equilibrium; Berendsen is neither, and Gromacs has said
  so at every grompp since 2025 --- unheard, because those warnings were being
  discarded (fixed in 2.13.0). This covers densification, precure and postcure
  equilibration, the CURE relax and drag ladders, and the ring cure's relax and
  equilibrate.

  The deformation stages are the exception: they force pcoupltype = anisotropic, which
  C-rescale does not support at all --- grompp errors outright --- so deform and
  clamped shear now set Parrinello-Rahman, which does support it and also samples
  the right ensemble. Isochoric shear has no barostat and is unaffected.

  This changes the sampled ensemble. Densities, glass-transition temperatures and
  moduli from earlier versions are not strictly comparable with ones produced now. That
  cost is deliberate and was taken on Cameron's decision, in the same spirit as the 2.7.0
  constraint change. tau_p is unchanged at 0.5 ps, so that if anything proves unstable
  there is only one variable to look at; it is the first knob to try.

  A test now fails if any packaged mdp reintroduces a deprecated barostat, or pairs
  C-rescale with the anisotropic coupling it cannot do.