-- When doing cross-species comparisons and studying population history and ancient DNA data, having SOME measure of confidence is needed at every single site that doesn't depend on the reference base, even in a naive per-site SNP mode. Old versions of GATK provided GQ and some wrong PL values at reference sites but these were wrong. This commit addresses this need by adding a new UG command line argument, -allSitePLs, that, if enabled will:
a) Emit all 3 ALT snp alleles in the ALT column.
b) Emit all corresponding 10 PL values.
It's up to the user to process these PL values downstream to make sense of these. Note that, in order to follow VCF spec, the QUAL field in a reference call when there are non-null ALT alleles present will be zero, so QUAL will be useless and filtering will need to be done based on other fields.
-- Tweaks and fixes to processing pipelines for Reich lab.