Small code review (added some comments)
Enhanced JSON parser feeding

JSONTarget: raw data is stored in the feeding list, the conversion to
string (if required) is done only once all data has been received.
This avoids errors decoding splitted wide-characters.
History becomes an optional parameter of ServerProxy

* Removes the potential memory hog (history was never cleared)
* Allows to have different instances of History for each ServerProxy
* Tests updated