Notable changes in Gromacs 4.5.5:
* Improved pdb2gmx -chainsep option and reintroduced the -merge option.
* Fixed mdrun file appending truncating files to 0 bytes when
continuation runs stopped before writing new output.
* Fixed COM pulling with multiple constraints checking the
convergence of one constraint instead of all.
* Fixed some dihedrals in sugars in Gromos53a5/6 working on the wrong atoms.
* AmberGS force field is now based on Amber94 instead of Amber96.
* Moved hydrogens in Charmm27 protein termini to separate
charge groups and added ACE and CT3 residue types.
* Many small fixes which avoid termination with fatal errors
or crashes in mdrun and tools.
* Many small updates to the manual pages of programs.
01641df47b