URL-parsing+rendering part of the first two new convops ready

### Description
This PR implements the parsing of URL plus the rendering in XML and JSON of the first (/v1/contextTypes) of the batch of new convenience operations. A second new conv op is prepared for but not terminated (/v1/contextTypes/{entityType})

What is missing is the mongo part (see '#if 0' in serviceRoutines).

I don't like too much NEW_CONVENIENCE_OPERATIONS, because NEW_ will become obsolete very soon. I'd prefer something more descriptive, such as TYPE_BROWSING_OPERATION or something like that.