[update] steppar: 'check' qualifier added, which enables the check for

                  new better parameter sets found in other (still running)
		  steppar proccesses. If a better parameter set is found,
		  the stepping is restarted. The maximal number of restarts is
		  given by the value of 'check'. Additionaly 'dchi2' gives the
		  minimal improvment of chi2 [percentage] leading to a restart.