Minor fixes, cleanup and added documentation

* sweble-wikitext 0449049...12bad4f (4):

    commit 12bad4f4ebac07785833a2ffc3428f740d1b63ff

        Cleanup and added documentation

    commit 1b69fe2ae169e8d90268c46e68e7fad952a4af0d

        Renamed {WikiConfig,ParserConfig}.createAstTextUtils() -> .getAstTextUtils()

        Added documentation/clarification

    commit 9c343ffe8c529e65df7628e224cbc81455e75f41

        Parser functions and tag extension now use special ctor for un-marshalling

    commit 8194d6549dd388b13397b0301c710f523b44bb88

        Fixed NPE in TreeBuilderInBody