Command 'dbjlr <record|*> <level>' calls the report method for
all JSON links in all records, or in one named record.
Added level and indent arguments to the jlif::report() method.
Added jlif::map_children() method for recursing through all
JSON links, plus dbJLinkMapChildren() and dbJLinkMapAll() APIs.
Implemented the report and map_children methods in the const
and calc link types.