* Add append() method to FileRepo classes to enable chunked uploading
* Change chunksessionkey to chunksession
* Remove echo json stuff
* Fix a multitude of bugs in my own code
* still to test: mwEmbed use of chunked upload
Session id is used by client request to specify its login data from cookie, so the session data, by extensions, is like a sort of request parameter. Also, WebResponse.php seems to be used for data actually sent to the client, like requested cookies.
* Moved all of the debugging/logic to WebResponse so it can be properly used elsewhere.
* A bit of cleanup so cookies set by $wgUser->setCookie() use $wgCookiePath as they should.
* Bug 14887: $wgEnablePersistentCookies has been added to allow for disabling of persistent cookies.