gromacs-5.1.0 beta patch

This reverts commit b148b715.

Fixes a potential problem in the following commits:
423d49bf
bb6178a2
(reported by C. Perego)

Same as 423d49bf applied to gmx 5.0

Needs gromacs to be repatched

it should works, but more tests are needed

Same as 55bc92d2
(written by Carlo), but in such a way that it results as a git mv