#6 Broadcast netpaste presence

[Haim Zlig]

Make all netpaste agents network aware.

broadcast every X seconds i'm Here packet using UDP.

Note: currently only after doing a network copy. a copy
event is discharged to the network and only active
agents will get it and update their list. note it the
broadcast should also contain the group, so only those
belonging to broadcaster update their "copy to list"