The 1.2 version of python-sscha.

Bugfixes, cleanup of documentation, and a better user experience.

The main target of this version would be:

1. A much more complete cluster interface, and the possibility to inherit the cluster class to add different calculators from quantum espresso.
2. A better I/O with the new powerful line-minimization introduced in 1.1, to avoid the gear wheel like oscillations in the frequencies, free energy, and gradients when plotting the results. (just select only the good steps).
3. New interface with the cellconstructor calculators working with mpirun (ASE FileIOCalculator from the last version does not).