SV: more flexibly find CNVkit versus GATK segmentation
SV: more flexibly find CNVkit versus GATK segmentation

Enables runs on CWL and heterogeneity analyses where we can infer from
file naming rather than configuration.

chapmanb/bcbio-nextgen,lbeltrame/bcbio-nextgen,a113n/bcbio-nextgen,vladsaveliev/bcbio-nextgen,a113n/bcbio-nextgen,lbeltrame/bcbio-nextgen,vladsaveliev/bcbio-nextgen,a113n/bcbio-nextgen,chapmanb/bcbio-nextgen,lbeltrame/bcbio-nextgen,vladsaveliev/bcbio-nextgen,chapmanb/bcbio-nextgen