The descendant has to implement the function
response (ctx: C; req: WSF_REQUEST): WSF_RESPONSE_MESSAGE
Added related features and class in WSF_ROUTER to be able to use agent easily.
- removed path_parameter
- added `item' to include WSF_REQUEST.item
- marked obsolete `parameter'
The goal is to remove confusion, remove URI_TEMPLATE specific `path_parameter'
and provide a way to use ctx.item (..) to also include meta variable, query, form, ... items
