Restored override of checkAcceptance method to ensure no unsupported tracks are added to combination track
Restored override of checkAcceptance method to ensure no unsupported tracks are added to combination track

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