vcf-consensus: Treat missing alleles as REF

git-svn-id: https://svn.code.sf.net/p/vcftools/code@951 19d466ce-640d-45be-954f-fad4d9839663
vcf-consensus: New -i option

git-svn-id: https://svn.code.sf.net/p/vcftools/code@952 19d466ce-640d-45be-954f-fad4d9839663
Vcf.pm: More informative error message when merging wrong ploidy Number=G fields

git-svn-id: https://svn.code.sf.net/p/vcftools/code@953 19d466ce-640d-45be-954f-fad4d9839663
Merge remote-tracking branch 'upstream'