pmx: Automated setup and analysis for alchemical perturbations

pmx (formerly pymacs) has started as a small bunch of classes to read structure files such as pdb or gro and trajectory data in gromacs xtc format. Over the years it has been extended towards a versatile (bio-) molecular structure manipulation package with some additional functionalities, e.g. gromacs file parsers and scripts for setup and analysis of free energy calculations.