Attempt to provide sensible defaults for GAMESS

  * This was mostly inspired by looking at the Gaussian
    format where defaults for molecule charge and
    multiplicity are given.

  * This change also introduces some sensible defaults
    regarding memory.

  * It is inherently incompatible with the use of external
    files (this should also be fixed I suppose) since you
    are forced to also provide the charge in such a case.

  * Another and possibly more clever solution would be
    to just include $CONTRL ICHARG=? $END because GAMESS
    does support reading several of the same input groups