Cigar parsing fixes
Cigar parsing fixes

P operator was being handled incorrectly in some places (it shouldn't
consume reference or read).

Some invalid SAM records that attempted to consume more read bases than
were provided would produce a crash during variant calling. For
consistency with similar invalid cases, these records are now ignored.

RealTimeGenomics/rtg-tools,RealTimeGenomics/rtg-tools,RealTimeGenomics/rtg-tools,RealTimeGenomics/rtg-tools