Fix naming from "Gromacs" to "GROMACS"

Fix naming from "Gromacs" to "GROMACS"

A bunch of user-facing names used the wrong name, so improved the
consistency there.

Fixing naming within source-code comments is not targeted here.

There's one or two fixes in the Doxygen comments, but that's not
targeted here. In particular, many references to "Gromacs" are in the
SIMD module, which would be silly to bump right now, since there are
lots of patches in Gerrit possibly affected.

Change-Id: I83f1414bffa322dbe2756dc4e5902342ac5fa2a5