implement sensor range requirements

src/lib/config/ShipsConfig.h

@@ -33,6 +33,11 @@ struct ShipMovement
     Formula speedFormula;  // REQ-SHP-STATS, REQ-SHP-MOVEMENT
 };
 
+struct ShipSensor
+{
+    Formula sensorRangeFormula;  // REQ-SHP-SENSOR, REQ-SHP-STATS
+};
+
 struct ShipCombat
 {
     Formula damageFormula;
@@ -69,6 +74,7 @@ struct ShipDef
     ShipThreat threat;
     ShipHealth health;
     ShipMovement movement;
+    ShipSensor sensor;
     ShipLoot loot;
 
     // Role-specific sections. A ship is a combat ship if combat is present,