#9 lnp priority fix

[Joseph Woolley]

I have found that lnp (specifically using dll to
transmit programs to the RCX) misses data from time to
time. To correct this, I increased the
packet_consumer process priority (to PRIO_HIGHEST+1)
then had to change the kill_all for the ON_OFF button
to kill_all(PRIO_HIGHEST+1)

Ralph Clark also reported problems with dll, and the
above fix seemed to work for him. (for the download
errors)