Made a fancier lasergun (#174)

Laserguns now have an internal capacitor that can be recharged by using it with a power cell

Makes the final fix for #138

Content.Server/GameObjects/Components/Power/PowerStorageComponent.cs

@@ -60,6 +60,7 @@ namespace Content.Server.GameObjects.Components.Power
         [ViewVariables]
         public bool Full => Charge >= Capacity;
 
+        public event Action OnChargeChanged;
         public override void ExposeData(ObjectSerializer serializer)
         {
             base.ExposeData(serializer);
@@ -70,6 +71,14 @@ namespace Content.Server.GameObjects.Components.Power
             serializer.DataField(ref _distributionRate, "distributionrate", 1000);
         }
 
+        protected virtual void ChargeChanged()
+        {
+            if (OnChargeChanged != null)
+            { //Only fire this event if anyone actually subscribes to it
+                OnChargeChanged.Invoke();
+            }
+        }
+
         /// <summary>
         /// Checks if the storage can supply the amount of charge directly requested
         /// </summary>
@@ -88,6 +97,7 @@ namespace Content.Server.GameObjects.Components.Power
             _charge = Math.Max(0, Charge - toDeduct);
             LastChargeState = ChargeState.Discharging;
             LastChargeStateChange = DateTime.Now;
+            ChargeChanged();
         }
 
         public virtual void AddCharge(float charge)
@@ -95,6 +105,7 @@ namespace Content.Server.GameObjects.Components.Power
             _charge = Math.Min(Capacity, Charge + charge);
             LastChargeState = ChargeState.Charging;
             LastChargeStateChange = DateTime.Now;
+            ChargeChanged();
         }
 
         /// <summary>