+3. centralise the invalid callsign check so that g1tlh1 and similar calls
+will not be allowed to login anymore.
+4. Fiddle with the lockout mechanism so that set/login g1tlh also locks out
+g1tlh-1 -> g1tlh-15 UNLESS one of these is specifically unlocked.
+5. Make sh/log only show stuff that sh/ann, sh/talk, sh/rcmd doesn't.