mapguide-react-layout viewer option for static map publishing

[jumpinjackie]

• [x] Add mapguide-react-layout viewer support to publish profile
• [x] Add mapguide-react-layout viewer template
• Add support for overlay layers
  • [x] WFS
  • [x] WMS
  • [x] GeoJSON external layers
  • [x] GeoJSON from MapGuide layers
    • [x] In local mode, set up custom drivers that know how to set up OL vector and vectortile layers from pre-existing data loaded in via <script> tags
• [x] BLOCKER: XmlConvert.SerializeXmlNode doesn't allow for certain elements to be explicitly serialized out to a certain type. This breaks our ability to define subject/external layer extension properties that are expected to be of a certain type. We need to make a fork of XmlNodeConverter to implement this missing logic (per: https://stackoverflow.com/questions/18611139/force-jsonconvert-serializexmlnode-to-serialize-node-value-as-an-integer-or-a-bo)