Fixed bug in min_coverage_observed calculation
File VCF: add_allele method to add allele to entry
File VCF: update to vcf4.2 using Number=R representing on value per ref and alts
File VCF: updated info_for_allele to return info for ref info type R
File VCF: add_allele adds info to A & R fields
GM: reader for instdata w/ annotation uses entry add_allele method
File VCF: update dbsnp parser to handle R info type number