* because it is not referentially transparent; normally we reserved parens for
side-effecting code but given how people thoughtlessly close over it we revised
that that decision for sender
* caller can still omit parens
* This can't go into 2.2.x since ScalaTest 1.9.2-SNAP2 has source incompatible changes and the dependecy in akka-multi-node-node-testkit would force people to upgrade.
- add more cross references to ActorDSL docs
- improve SBT command line for running the multi-node test
- correct small error in Restart Hooks section of actors.rst
