* sensors bugfix + standardisation
standardises datums and events so they default to 0 opacity and require events to be set explicitly if opaque, instead of events working one way and the datums the other.
also fixes the sensor ping from setting every event to opaque every time it scans
* cl
* fixes events going transparent by toggling sensors on and off
* better solution - doesn't leave blocked vision on overmap when toggling
toggling sensors doesn't leave opaque tiles on the overmap doing it like this
* just rewording cl, no code change here
Llywelwyn