vcf2maf v1.6.4

• Handle undefined Tumor_Seq_Allele2
• More stringent about reference genome mismatches
• Handle missing ALLELE_NUM when SV_TYPE defined in INFO
• Retain FILTER data from input VCF
• Add a filter called common_variant for variants with >0.04% minor allele frequency in any ExAC subpopulation, unless ClinVar says pathogenic, risk_factor, or protective