fix long-standing off-by-one bug where window cannot scroll all the way to the last base in the reference sequence
fix long-standing off-by-one bug where window cannot scroll all the way to the last base in the reference sequence

GreggHelt2/apollo-test,limeng12/jbrowse,SuLab/jbrowse,nathandunn/jbrowse,SuLab/jbrowse,GreggHelt2/apollo-test,igemsoftware/Shenzhen_BGIC_0101_2013,GreggHelt2/apollo-test,GreggHelt2/apollo-test,SuLab/jbrowse,erasche/jbrowse,nathandunn/jbrowse,Arabidopsis-Information-Portal/jbrowse,SuLab/jbrowse,Arabidopsis-Information-Portal/jbrowse,erasche/jbrowse,erasche/jbrowse,igemsoftware/Shenzhen_BGIC_0101_2013,limeng12/jbrowse,erasche/jbrowse,Arabidopsis-Information-Portal/jbrowse,Arabidopsis-Information-Portal/jbrowse,igemsoftware/Shenzhen_BGIC_0101_2013,igemsoftware/Shenzhen_BGIC_0101_2013,GMOD/jbrowse,GMOD/jbrowse,GMOD/jbrowse,GMOD/jbrowse,erasche/jbrowse,SuLab/jbrowse,igemsoftware/Shenzhen_BGIC_0101_2013,igemsoftware/Shenzhen_BGIC_0101_2013,GMOD/jbrowse,Arabidopsis-Information-Portal/jbrowse,limeng12/jbrowse,GreggHelt2/apollo-test,erasche/jbrowse,limeng12/jbrowse,erasche/jbrowse,limeng12/jbrowse,SuLab/jbrowse,limeng12/jbrowse,GreggHelt2/apollo-test,erasche/jbrowse,Arabidopsis-Information-Portal/jbrowse,igemsoftware/Shenzhen_BGIC_0101_2013,limeng12/jbrowse,nathandunn/jbrowse,Arabidopsis-Information-Portal/jbrowse,igemsoftware/Shenzhen_BGIC_0101_2013,GreggHelt2/apollo-test,limeng12/jbrowse,SuLab/jbrowse,nathandunn/jbrowse,nathandunn/jbrowse