Add UDP.recv and udp_recv

[postmodern]

To compliment UDP.send and udp_send, there should be UDP.recv and UDP::Mixin#udp_recv methods. These methods should call connect with the host and port arguments, then calls .recv(1024) to read the first chunk of data sent through the connection. This method is similar to UDP.banner and udp_banner, but it reads the whole packet of data and doesn't stop at the first newline.

data = UDP.recv(host,port)
data = UDP.recv(host,port, length: 4096)

include Network::UDP::Mixin

data = udp_recv(host,port)
data = udp_recv(host,port, length: 4096)