Refactor WindupProcessor/Impl to simplify the API, move inner classes out and offload part of the code like prettyPrintRule() out of this important class.

During the meeting, we agreed that:

1) Generally, the direction of moving the config of parts of windup into ~Config classes is better than overloading methods.
2) Automagical lazy initialization of low-level things is not desirable, as it makes the exec flow less readable. Ideally, initialization should happen at very predictable places, i.e. a call to GraphContext#init( GraphContextConfig ).