updated checking of valid chromosome to be 'defined' due to '0' as a name for a chromosome
updated checking of valid chromosome to be 'defined' due to '0' as a name for a chromosome

LyonsLab/coge,asherkhb/coge,asherkhb/coge,asherkhb/coge,asherkhb/coge,LyonsLab/coge,asherkhb/coge,asherkhb/coge,asherkhb/coge,LyonsLab/coge,LyonsLab/coge,asherkhb/coge,asherkhb/coge,LyonsLab/coge,LyonsLab/coge,LyonsLab/coge,LyonsLab/coge,LyonsLab/coge