Corrected ISICSoo class version

The Coster–Kronig enhancement factor calculation for M3 shell x-ray production cross sections was found to be incorrect in both ISICSoo class (Batic et al. (2012) [1]) and isics program (Cipolla (2013) [2]). The affected functions of ISICSoo class have been corrected. The resulting X-ray production cross sections are modified by less than 15%, while ionization cross sections are unchanged.