Function request: Get list of ESP servers

This is a request for a new function that would return URLs for the currently-attached ESP servers for a cluster, similar to the existing Std.System.Thorlib.DaliServer() function. In fact, this new function could be placed into the Thorlib module as well.

Full URLs would be preferrable, as they can be dropped into SOAPCALL functions easily without having to worry about parsing for HTTPS, port number, etc..