New Rules for AsParallel

[jass790909]

Hi,
I would like to suggest a new rule for PLinq that AsParallel should pair up with WithDegreeOfParallelism.

SomeEnumerable
         .AsParallel()
         .WithDegreeOfParallelism(someNumber)
         ...

In our case, we are sending hundreds web requests parallelly, however, we don't want to create so many threads at the same time.
As discussion with Brian yesterday, sending request is an IO bound function and therefore we could have this new rule to our project.