close #380

This bug was reported by Carol Simoes and fixed by Javi Iglesias.

The fix requires resetting a regtest.

update GMX2018.3 accordingly
- including API check

* OpenMP changes to allow setting the number of threads from main code
furthermore avoiding to call getenv more than once (it is faster)

* setOpenMP: gromacs patch enabled to set the number of openMP threads

* OpenMP: moved static variables inside  a struct/function couple

* OpenMP: removed api interface and gromacs patch

* astyle

defined then just use one thread

@giovannibussi right?

- dumpgrid
- pca
- mds