Wall lights now require light bulbs. (#151)

* Adds light_tube.rsi

Sprites taken from CEV Eris!

* Adds LightBulbComponent

* Wall lights now use light bulbs!

* Light bulb now updates its sprite when it changes.

* Comments the code.

* Adds license and copyright to new sprites

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

@@ -0,0 +1,71 @@
+using System;
+using SS14.Server.GameObjects;
+using SS14.Shared.Enums;
+using SS14.Shared.GameObjects;
+using SS14.Shared.Serialization;
+
+namespace Content.Server.GameObjects.Components.Power
+{
+    public enum LightBulbState
+    {
+        Normal,
+        Broken,
+        Burned,
+    }
+
+    public enum LightBulbType
+    {
+        Tube,
+    }
+
+    /// <summary>
+    ///     Component that represents a light bulb. Can be broken, or burned, which turns them mostly useless.
+    /// </summary>
+    public class LightBulbComponent : Component
+    {
+
+        /// <summary>
+        ///     Invoked whenever the state of the light bulb changes.
+        /// </summary>
+        public event EventHandler<EventArgs> OnLightBulbStateChange;
+
+        public override string Name => "LightBulb";
+
+        public LightBulbType Type = LightBulbType.Tube;
+
+        /// <summary>
+        ///     The current state of the light bulb. Invokes the OnLightBulbStateChange event when set.
+        ///     It also updates the bulb's sprite accordingly.
+        /// </summary>
+        public LightBulbState State
+        {
+            get { return _state; }
+            set
+            {
+                var sprite = Owner.GetComponent<SpriteComponent>();
+                OnLightBulbStateChange?.Invoke(this, EventArgs.Empty);
+                _state = value;
+                switch (value)
+                {
+                    case LightBulbState.Normal:
+                        sprite.LayerSetState(0, "normal");
+                        break;
+                    case LightBulbState.Broken:
+                        sprite.LayerSetState(0, "broken");
+                        break;
+                    case LightBulbState.Burned:
+                        sprite.LayerSetState(0, "burned");
+                        break;
+                }
+            }
+        }
+
+        private LightBulbState _state = LightBulbState.Normal;
+
+        public override void ExposeData(ObjectSerializer serializer)
+        {
+            serializer.DataField(ref Type, "bulb", LightBulbType.Tube);
+        }
+
+    }
+}