get VCF backend regularizing refseq names properly, references #239
bugfix to `Alignments` track, does not handle maxHeight correctly
speed up refSeqOrder generation in Browser.js.  if no `refSeqOrder` defined in configuration, the reference sequences will not be sorted
add `commifyNumber` to JBrowse/Util as a synonym for `addCommas`
some more BAM error handling improvements
fix maxheight message z-index