Adds slippery items (#1321)

* Start work on Slippery Component

* Slips work

* Add banana peel

* Add required slip speed

* Add slip sound

* Adds soap

* Make soapnt, soapsyndie and soapdeluxe inherit soap

* Adds homemade soap and omega soap

* Fix slipping not taking into account the entity being in a container

Content.Server/GameObjects/EntitySystems/SlipperySystem.cs

@@ -0,0 +1,26 @@
+using Content.Server.GameObjects.Components.Movement;
+using Robust.Shared.GameObjects;
+using Robust.Shared.GameObjects.Systems;
+
+namespace Content.Server.GameObjects.EntitySystems
+{
+    public class SlipperySystem : EntitySystem
+    {
+        public override void Initialize()
+        {
+            base.Initialize();
+
+            EntityQuery = new TypeEntityQuery(typeof(SlipperyComponent));
+        }
+
+        public override void Update(float frameTime)
+        {
+            base.Update(frameTime);
+
+            foreach (var entity in RelevantEntities)
+            {
+                entity.GetComponent<SlipperyComponent>().Update(frameTime);
+            }
+        }
+    }
+}