Log Message:
Update to Gromacs 4.5.4:

* Fixed pdb2gmx picking up force field from local instead of
library directory
* Made pdb2gmx vsite generation work again for certain His namings.
* Fixed incorrect virial and pressure averages with certain
nst... values (instantaneous values correct)
* Fixed incorrect cosine viscosity output
* New -multidir alternative for mdrun -multi option
* Several minor fixes in analysis tools
* Several updates to the program documentation