VarDict: avoid calling SVs with vardict-perl
VarDict: avoid calling SVs with vardict-perl

Improve runtimes for small variant calling and avoid large events that
span outside of target regions, resulting in VCF merge issues.

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