#24 Allow mismatch of ALT and REF bases for vcf-merge

[Thon de Boer]

It seems that vcf-merge will throw an exception when the REF and ALT bases in one of the VCF's don't match the other. I understand why this would be, but I have a usecase where this may be possible..

I would like to be able to ignore this discrepancy in mismatched ALT and REF bases (. should be acceptable) and maybe it should not throw an exception when the -s flag is active in that case