Implemented SerialSubscription and Timeout operator

[johnhmarks]

Implemented Timeout operator and SerialSubscription upon which it is based.

[cloudbees-pull-request-builder]

RxJava-pull-requests #345 SUCCESS
This pull request looks good

[benjchristensen]

I think this class is achieving the same as MultipleAssingmentSubscription. Can you take a look at it?

https://github.com/Netflix/RxJava/blob/master/rxjava-core/src/main/java/rx/subscriptions/MultipleAssignmentSubscription.java

No idea why I wrote such a horrible Javadoc on it that doesn't explain it well. From the MSDN doc it states: "Represents a disposable whose underlying disposable can be swapped for another disposable."

Your Javadoc description should replace the MultipleAssingmentSubscription one if I'm reading the code correctly and they do the same things.

[johnhmarks]

Hi Ben,

SerialSubscription and MultipleAssignmentSubscription are different things. MultipleAssignment simply enables you to swap out the underlying subscription in a thread-safe manner. Whereas, Serial unsubscribes from the previous underlying as you replace.

See:
http://msdn.microsoft.com/en-us/library/system.reactive.disposables.serialdisposable(v=vs.103).aspx
Vs:
http://msdn.microsoft.com/en-us/library/system.reactive.disposables.multipleassignmentdisposable(v=vs.103).aspx

[benjchristensen]

Ah okay, cool.

[benjchristensen]

Merging this as it functions and is well written and well documented and will then look at whether modifications based on #446 make sense.