made algebraic datatype called Alignment in Pileup which combines the cigar operator and sequenceRead and statically captures the invariant that deletions have an empty sequenceRead, and Match/Mismatch have only one character

rename chr/seq to base/bases
rebase off master
Merge pull request #27 from hammerlab/cigar_adt

made algebraic datatype called Alignment in Pileup which combines the...