Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Flush stdout after each line to make piping to another command easier.

update for new events

sync w/ p4: minor cleanups to improve msgs

update copyright's

o fix join/rejoin format
o add netbsd portability glue

MFC after: 2 weeks

o move programs to separate directories and use stock Makefiles;
this simplifies including them in crunchgen images
o rename 80211* programs to wlan* as was originally intended