Improvements to GROMACS tools

gmx pdb2gmx now resolves generated hydrogen names from the residue topology

When gmx pdb2gmx adds hydrogens from the hydrogen database, it now looks up their names in the residue topology entry of the selected force field instead of relying on hard-coded numbering rules. This allows force fields that use different hydrogen naming schemes, such as original AMBER/IUPAC names for methylene hydrogens, to work without naming-specific code paths or command-line options.

-w now displays more file types, and falls back to other viewers

The -w option can now display .cif and .gro files, neither of which had a viewer before. Every file type it handles now lists several viewers rather than one: the viewer used previously is still preferred, and an alternative is chosen only when that one is not installed, so -w now works on machines where it used to fail. Structures are shown with PyMOL, ChimeraX, Jmol or VMD, plots with Grace, and images and PostScript with the common desktop viewers. The GMX_VIEW_ environment variables continue to override the choice.