Initial check-in
Initial check-in
resurrected improvements to Groupers

1. change to AbstractRxStage, and use the stage metering
2. remove the latch better in snowshovels
resurrected improvements to Groupers

1. change to AbstractRxStage, and use the stage metering
2. remove the latch better in snowshovels
efficient concurrent objects
desired dir structure for grouper src
Merge branch 'master' of ../REEF-extraction
desired dir structure for test grouper
Merge branch 'master' of ../REEF-extraction