Give applications the option of more forcefully terminating client
connections for asyncio servers. Useful when terminating a service and
there is limited time to wait for clients to finish up their work.

We want to be able to detect if the application fails to keep track of
the transports, so we cannot keep them alive by using a hard reference.

The application might be waiting for all transports to close, so we need
to properly inform the server that this transport is done.

One could be made clearar, and the other is probably superfluous.

Try to get the streams and the kernel in to a more deterministic state
by specifying fixed buffering limits.

No possibly infinite loop. Instead ask the system how much buffer space
it has and fill that.

…close

In case it takes some time, as we need access to the server side
stream objects to perform the test.