It's pretty confusing when a CObject is owned both by its parent-child
relationship, but also by an ObjectPtr member in the parent.
In those cases, we have to make sure we both unparent the child *and*
reove it from the ObjectPtr.
This will become a bit less confusing when ObjectPtr becomes RefPtr,
although still not crystal clear. I'm not sure what the solution is.
Subclasses of CNetworkJob handle this by overriding shutdown().
This patch implements it for CHttpJob by simply tearing down the
underlying socket.
We also automatically call shutdown() after the job finishes,
regardless of success or failure. :^)
The C_OBJECT macro now also inserts a static construct(...) helper into
the class. Now we can make the constructor(s) private and instead call:
auto socket = CTCPSocket::construct(arguments);
construct() returns an ObjectPtr<T>, which we'll later switch to being
a NonnullRefPtr<T>, once everything else in in place for ref-counting.
Now there's just CHttpRequest::set_url(URL), no need to specify the
host, port and path manually anymore.
Updated ChanViewer and Downloader for the API change.
