initial attempt at implementing periodic schedulers as discussed in #228, needs some testing next...
manually merging master in...
fixing the scheduler methods to fit the new pattern
taken over default recursive implementation
Fixed scheduler javadoc, and one single unnecessary cast in takeWhile
Fixed a bug in the test scheduler that happened when advancing time by a too little amount
Fixed millisecond/nanosecond confusion in test scheduler, fixed schedulePeriodically to use now() instead of System.nanoTime() and added a test against scheduling periodically
Tested unsubscription, too
switched OperationInterval implementation over to use periodic scheduling
ExecutorScheduler now uses scheduleAtFixedRate instead of recursion when possible.
Removed unused imports.
Merge pull request #246 from jmhofer/schedulePeriodically

Scheduling actions periodically