make the hierarchical tracksel save the open/closed state of its categories in localstorage, if the browser has it.
make the hierarchical tracksel save the open/closed state of its
categories in localstorage, if the browser has it.

limeng12/jbrowse,GMOD/jbrowse,nathandunn/jbrowse,nathandunn/jbrowse,Arabidopsis-Information-Portal/jbrowse,Arabidopsis-Information-Portal/jbrowse,limeng12/jbrowse,Arabidopsis-Information-Portal/jbrowse,Arabidopsis-Information-Portal/jbrowse,limeng12/jbrowse,GMOD/jbrowse,erasche/jbrowse,erasche/jbrowse,limeng12/jbrowse,nathandunn/jbrowse,limeng12/jbrowse,Arabidopsis-Information-Portal/jbrowse,limeng12/jbrowse,limeng12/jbrowse,erasche/jbrowse,erasche/jbrowse,nathandunn/jbrowse,erasche/jbrowse,Arabidopsis-Information-Portal/jbrowse,nathandunn/jbrowse,erasche/jbrowse,Arabidopsis-Information-Portal/jbrowse,GMOD/jbrowse,GMOD/jbrowse,GMOD/jbrowse,erasche/jbrowse,limeng12/jbrowse,erasche/jbrowse