code cleanup
updates
http: remove unnecessary error messages
x0d director: code cleanup
[http] HttpConnection: minor optimization / code cleanup.

ref/unref only the critical region instead the complete readSome()-body.
x0d: some NDEBUG-ification
updates
http director cache implementation improvements

* fixed bug that caused some requests to hang forever when main request to the same entity caused queuing but the entity is not subject to be cached.
* code refactors in order to introduce Vary-support soon
* json output: stats are sub-namespaced by "stats" object
* implements object-cache configuration loading/updating/saving
* internal timespan numbers in JSON/config API changed unit from milliseconds to seconds.
* adds main function director.cache(bool)
* adds main function director.cache.key(string)
* adds main function director.cache.ttl(timespan)
* documentation updates
* vim syntax file adapted to implementation changes