added info to dead event handler
added missing events to gui
clarified naming (Source Connection)
moved setSource to constructor argument
added constructor for type-only
added comments
added handling of sending and receiving PING and PONG
adde ms measurement
fix nothing selected on ping
closing of conection more separated
added function to disconnect
connection more separate
removed setSourceConnection
removed ping from connection. (it is only a message)
let Connection return InetEddress
added empty-constructor for UDP
added new notification types
added lost connection event
added timekeeper for synchronization
wont't start if udp cant be established
measure pingpong now with nanosecs
added class for UDP connections