SV: PURPLE progress -- initial COBALT integration
SV: PURPLE progress -- initial COBALT integration

PURPLE requires genomes split into 1000bp windows, so currently
not possible to use CNVkit's flexible target/anti-target binning
as an input. Will need to use COBALT directly, so added notes
and skeleton. Still not a functional implementation #2532

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