
This calls a function from a SOAP server and returns the result as a return value.
Params is an array of (Parameter name, Value) pairs representing the parameters
passed in the SOAP call.  Each of these pairs become an XML sub-entity
of the procedure entity.  The return value of the function is the entity
inside the SOAP body of the response.  In debug mode the return value is an
array of 3 elements; the non-debug return value (if any) as element 0, the XML
text of the request as element 1 and the XML text of the server response
as element 2.  This function does not use any XML types when creating the
XML.  It represents types as a cast to varchar would, with one
exception - dates and times according to ISO8061.
