#65 Fire key should use different command

[Andreas Kirschbaum]

When firing to north, the clients seem to send "fire
1", then "fire_stop". Instead it should send "north f"
(note the trailing "f" to the north command.)

I think using the "north f" command is preferrable
since it uses less bandwith, and also prevents very
slow players from casting multiple spells for one key
press.