possible define a single molecule with PSFs of fragments and explicitly declaring
the further terms.. This required a reorganization both of the input sections (sorry about that guys!!)
but also in the code handling the reading and post_process of PSF info.
Few regtests added and changed the syntax of MOL_SET in MC regtests.
Added also a preliminary section of the new free energy method(not working yet).
svn-origin-rev: 5958
