[Gradle Release Plugin] - pre tag commit:  '0.20.0-RC1'.
[Gradle Release Plugin] - new version commit:  '0.20.0-RC2-SNAPSHOT'.
Version 0.20.0-RC1
first pass at javadocs for new backpressure stuff
Zip with Backpressure Support

This supports both upstream and downstream backpressure.
RxScala: Add Scala idiomatic methods
Merge pull request #1448 from zsxwing/rxscala-more

RxScala: Add Scala idiomatic methods
New test case for takeWhile that currently fails
Fix issue #1451
Fix related classes for issue #1451
OperatorAll & Backpressure

Similar to filter, it needs to request(1) each time it filters an onNext.
Debugging Test
Merge pull request #1446 from benjchristensen/zip-backpressure

Zip with Backpressure Support
Merge pull request #1454 from zsxwing/issue1451

Fix issue #1451
Merge pull request #1453 from spodila/takeWhileFailure

New test case for takeWhile that currently fails
MergeDelayError & OnErrorFlatMap w/ Merge
Merge pull request #1457 from benjchristensen/mergeDelayError-backpressure

MergeDelayError & OnErrorFlatMap w/ Merge
Remove test ... leave functional testing in core

The behavior of mergeDelayError has slightly changed.

It doesn't eagerly unsubscribe if the source keeps emitting after onError.
Removing unnecessary test
Removing unnecessary test