Working on Porp that goes and returns...exciting stuff!

* Reshaping Porp fluent methods.
* Thoughts on moving forward...
    * Crux comes down to how to turn a process that is essentially two
      one-way processes into a duplex async process.
    * I think the way to do it is on the Sender node...have *IT* store
      the continuation function for on return, and that function is
      wrapped in a TaskCompletionSource.
    * The consumer can then use the async/await paradigm without any
      problems, and there is no mess with trying to pass continuation
      function state along the ride for the porp (It's stuff that is not
      needed for the first part of the journey anyway, so this makes
      sense).


Signed-off-by: William Raiford <bill.mybiz@gmail.com>