* also make factories more consistent by only offering
FlowGraph.create()
* also remove secondary (edge-based) FlowGraph.Builder DSL
* also improve naming for conversions from Graph to
Source/Flow/BidiFlow/Sink
This necessitates the removal of method overloading in the Java Graph
DSL: the to() and via() methods were not otherwise resolved correctly by
javac, leading to incomprehensible error messages. The new approach is
to offer just one way of doing things which is a bit more verbose but
should be easier to read and learn. In this vein auto-importing while
using the DSL is also gone for Java—not sure about Scala yet.
* Remove name parameter (no overloads), naming is performed using `.withAttributes` or the new
convenience `.named`. Those adds the OperationAttribute.Name and also change the name of the
shape Inlet and Outlet.
* Remove Source/Sink parameter list for 0 parameter methods,
this allows usage of `Sink.head` instead of `Sink.head()`
* FlowMaterializer is now the actor independent interface
* ActorFlowMaterializer is the actor based interface
* MaterializerSettings renamed to ActorFlowMaterializerSettings
* impl.ActorBasedFlowMaterializer renamed to impl.ActorFlowMaterializerImpl
* Optimizations included in ActorFlowMaterializerSettings
* Note that http is using FlowMaterializer in api, but I suspect that it
will currently only run with a ActorFlowMaterializer
