First attempt at "sample" operator. Should probably use "interval"
operator instead of an internal clock. Also still needs tests!
Merge branch 'interval' into sample
Switched sample from internal clock to using the interval operator
Added a unit test against the sample operator
initial attempt at implementing periodic schedulers as discussed in #228, needs some testing next...
Moved state to Observer from Observable
manually merging master in...
fixing the scheduler methods to fit the new pattern
taken over default recursive implementation
Merge branch 'master' into sample
added missing linebreak
Fixed scheduler javadoc, and one single unnecessary cast in takeWhile
Merge branch 'master' into multisubscribe

Conflicts:
	rxjava-core/src/main/java/rx/operators/OperatorGroupBy.java
Merge branch 'master' into multisubscribe

Conflicts:
	rxjava-core/src/main/java/rx/operators/OperatorGroupBy.java
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.