making Func0 covariant in its return type, cleaning up a few warnings, removing a bit of unused code
added variance to Func1 (hopefully) everywhere...
added variance to Func2, too
added variance to all other Func*; this breaks Scala for good, it seems, as long as Observable remains invariant
added variance to Action*, too
lots of Observer<? super X>
updated to Scala 2.10.2 again, repaired Scala tests, generalized two more zip methods
UnitTest confirming compilation failure without super/extends and success with them.

- only testing zip operator at this time
Need to stay pinned on Scala 2.10.1 still …

I can't get through release process to maven central on 2.10.2 for some reason so pinning until that is solved.
Zip: Order of Generics and Artities 5-9

Changed order of generics on zip (and combineLatest) to match the rest of the project.
Added arties 5, 6, 7, 8, 9 to zip operator.

https://github.com/Netflix/RxJava/issues/333 Order of Generics on Zip Operator
https://github.com/Netflix/RxJava/issues/103 Add more arities to zip operator
Merge pull request #1 from benjchristensen/super-extends-additions

Zip and CombineLatest Operators: Generic Order and More Arities
adapted RxImplicits tests againt zip to new generics order, renamed two more reduceFunctions to zipFunction
generalized everything in Observable that deals with covariance of observables
Timestamped, Notification and Future are now also treated as covariant
added an unnecessary explicit cast because the Jenkins java compiler is unhappy otherwise?
Generalized all the operators, too
generalized BlockingObservable and the execution hook further
added a few 'compiler' tests
removed some <? super Throwable>s because that's rather unnecessary
Merged in master so that the gradle pull request build has a chance to work again