Move upstream tracking state off Action and expand PushSubscription scope
Implement Predicate in Selector
Change ignoreErrors to fit more with its purpose, adding also ignoreError on predicate
Misc fixes and stability
refactor parallel() operation to use a function instead of emitting stream of stream.
Fix most of the remaining tests fail
TODO: capacity tracking issue in parallel, complete signal issue in nested zip stream.
Work towards passing tck with flatmap and zip while protecting ringbuffer from overrunning, still having issues with some tests.
All tests pass, after some work on zip and subscription. More to explore later, for now, having some rest