udp client: add try-catches around close()
udp client: unref the socket
udp client: don't set a timer for stopped message
simplify server tests
make large torrent test not depend on the network

for #18
timeout might not be defined
wait for server close before next test
Revert "udp client: unref the socket"

This reverts commit 6f1aa981d42169c794b97879bbc2d3e6cf3c8d5d.

Conflicts:
	index.js
udp client: clean up timer situation
make magnet test work offline

for #18