change to remove complex alleles from vcfindels output

Strictly require only that the ref and alt alleles are not the same length.
Previously, any time the reference allele was >1bp we kept.  This is better
achieved via vcfnosnps.
added method to strip out biallelic SNPs from VCF file
fixing minor errors

vcfnobiallelicsnps was excluding multiallelic snps
Merge https://github.com/ekg/vcflib