Orbital Ion Cannon 1.4.6

The ion cannon GUI hotkey now only works when there is at least one cannon in orbit.
Added config option for adjusting how much area Auto-Targeting Stations permanently reveal around themselves.
Reduced "Ion Cannon Ready" spam when firing several ion cannons -- the minimum duration between announces can be found in config.lua.
Renamed custom "on_ion_cannon_fired" event to "on_ion_cannon_targeted", to better reflect that it fires on target designation rather than actual blast impact.
The "on_ion_cannon_targeted" event position is no longer slightly off-center, and now also passes an event.radius variable.