handle BAM reads that have an MD but no CIGAR, fixes #330
make FeatureFiltererMixin more powerful, add ability to remove individual filters from the filter chain
add support for supplementary_alignment flag to BAM features, make qc_failed, duplicate, and secondary_alignment flags visible in tags() on non-multi-segment reads
Added options to Alignments2 tracks to allow hiding reads that are
duplicates, fail vendor QC, have missing mate pairs, are secondary
alignments, and/or are supplementary alignments.  References #332.
update quick-start tutorial to suggest --trackType CanvasFeatures in the flatfile-to-json.pl blurb, references #326
make SNPCoverage tracks use the _MismatchesMixin, and uniqify the mismatches returned by _getMismatches to avoid double counting.  fixes #335
update release notes
add support for an `addStores` URL query variable, fixes #336