synchk: Be explicit in what fields we send to clients.
Make sure put the request's filename in the errors to avoid reporting errors in the wrong file.
The latter is a sife-effect of the cache being based on content rather than filename,
so if you rename a file, you'd see errors for the wrong file.
Report the decoding time of requests separately from the overral request to make it easier to debug
If a request is made to an invalid method, include the list of available methods in the error message
Fix use of undefined var c