Defines utility functions and iterator interface for OpenMendel genetic variant packages: SnpArrays.jl (PLINK 1 .bed, .bim, .fam), VCFTools.jl (Variant Call Format .vcf), BGEN.jl (Oxford BGEN .bgen), and PGENFiles.jl (PLINK 2 .pgen, .pvar, .psam). Intended to be used in GWAS packages (OrdinalGWAS.jl, TrajGWAS.jl, MendelGWAS.jl (?)).