Name recv() based a "simplistic", as it can't work robustly in every
environment. All this is to let people concentreate on proper, read()-
based one (and to turn recv() based into a "negative showcase",
explaining what are the pitfalls of such approach).
Since "read-exactly" stream refactor, where stream.read(N) will read
exactly N bytes (unless EOF), http_server* examples can't any longer do
client_socket.read(4096) and expect to get full request (it will block
on HTTP/1.1 client). Instead, read request line by line, as the HTTP
protocol requires.
Per new conventions, we'd like to consistently use "u*" naming conventions
for modules which don't offer complete CPython compatibility, while offer
subset or similar API.
It's no longer intended to provide just "raw" socket interface, may include
some convenience methods for compatibility with CPython socket - but anyway
just minimal set required to deal with socket client and servers, not wider
network functionality.