Ranch now accepts connection asynchronously through a separate process. The accept process is linked to the acceptor, calls accept and does nothing else but send the socket back to the acceptor. This allows us to receive messages in the acceptor to handle upgrades instead of polling. This will also allow us later to make acceptors system processes. Remove support for connection pools in favor of a simpler max_connections setting. Connections can be removed from the count, allowing us to have as many long-lived connections as we want while still limiting the number of short-lived ones. Add max_connections, max_connections with long-lived connections, and upgrade tests.
ranch:get_port/1 returns the given listener's port.
Also use one export per line to improve future diffs. Bump the version to 0.2.1 to reflect this change.
Modules were renamed. The 'cowboy_' prefix became 'ranch_'. At the same time, ranch_ssl_transport became ranch_ssl, and ranch_tcp_transport became ranch_tcp, because appending '_transport' felt a bit redundant considering SSL and TCP clearly are transports. One test has been added to make sure everything is working.