Tons of changes

I've begun work on an OData data source type.  This will be used to
communicate with an OData-compliant service that serves as the backend
for the application in production.

The ArcGIS REST API may get used some, but anything that needs editing
will have to be done via OData, as ArcGIS can't actually edit a database
without using all the elaborate SDE business, which makes it slow and
horrible.