Trying Reactor/Meltdown out
Bringing back sleeps (b/c of new Reactor type)
Add splitter, improve multiplexer.
Add debugging utils
Remove debugging statement
Add some debugging primitives
Start porting tests to countdown latch
Cleanup windows tests
Extend perf tests
Port tests to latch, add commutative aggregator
Add topology building DSL
Cleanup
Add tests for rollups
Add buffer and rollup
Add pretty-printing
Fix multicast tests
Update utils to latest snapshot
Make more sensible pprint for transformer
Minor fixes
Fix problem with rollups expiring twice as late as they are supposed because of tick periods (now 10 times smaller than timeout)