Split cHTTPConnection implementation into a separate file.
Fixed parsing and implemented write nofitication.

The web connection finally works with a browser.
Fixed leaking HTTPRequest objects
Added cHTTPServer callbacks; fixed keep-alives.

The HTTP server now calls callbacks specified in its start function (debugified atm.) and it processes multiple requests on a single connection.
Added UserData to cHTTPRequest.

Callbacks may store one pointer of per-request data in the cHTTPRequest object. The object doesn't touch this data (doesn't own it).