- add referrer self-redirect check and test case
- dispatching: cleanup wbrequestresponse, move tests to a seperate file
- wbrequest: store both rel_prefix and host_prefix, with wb_prefix either full
or rel path as needed, so that full and relative paths are
both available in wbrequest
- create WbUrlHandler to differentiate handlers which
support WbUrl (timestamp[mod]/url) semantic vs other request handlers.