fix bug in HTMLFeatures subfeature centering that was exposed at higher zoom levels on BAM tracks
fix bug in HTMLFeatures subfeature centering that was exposed at higher zoom levels on BAM tracks

SuLab/jbrowse,SuLab/jbrowse,erasche/jbrowse,igemsoftware/Shenzhen_BGIC_0101_2013,nathandunn/jbrowse,Arabidopsis-Information-Portal/jbrowse,nathandunn/jbrowse,igemsoftware/Shenzhen_BGIC_0101_2013,limeng12/jbrowse,GMOD/jbrowse,SuLab/jbrowse,erasche/jbrowse,limeng12/jbrowse,GMOD/jbrowse,GMOD/jbrowse,Arabidopsis-Information-Portal/jbrowse,limeng12/jbrowse,limeng12/jbrowse,erasche/jbrowse,SuLab/jbrowse,SuLab/jbrowse,SuLab/jbrowse,limeng12/jbrowse,nathandunn/jbrowse,Arabidopsis-Information-Portal/jbrowse,Arabidopsis-Information-Portal/jbrowse,limeng12/jbrowse,nathandunn/jbrowse,igemsoftware/Shenzhen_BGIC_0101_2013,igemsoftware/Shenzhen_BGIC_0101_2013,erasche/jbrowse,Arabidopsis-Information-Portal/jbrowse,igemsoftware/Shenzhen_BGIC_0101_2013,erasche/jbrowse,GMOD/jbrowse,GMOD/jbrowse,SuLab/jbrowse,limeng12/jbrowse,Arabidopsis-Information-Portal/jbrowse,erasche/jbrowse,igemsoftware/Shenzhen_BGIC_0101_2013,erasche/jbrowse,erasche/jbrowse,Arabidopsis-Information-Portal/jbrowse,limeng12/jbrowse,nathandunn/jbrowse,igemsoftware/Shenzhen_BGIC_0101_2013,igemsoftware/Shenzhen_BGIC_0101_2013