Explosions and Grenades, Triggers, OnDestroy, OnExAct, Fueltanks and destructible tables (#247)

* initial explosiveComponent

* remove garbagee

* assets

* tile mass deletion baby

* grenades

* tweaks

* Update Content.Server/GameObjects/Components/Explosion/ExplosiveComponent.cs

Co-Authored-By: Pieter-Jan Briers <pieterjan.briers@gmail.com>

* Ex_act based on damage, fixes and tweaks

* One finishing touch

Done the most cringe way

* ex_act explosions, tables are destructible now

also adds fuel tanks

* adds ex_act to mobs

Content.Server/GameObjects/EntitySystems/ActSystem.cs

@@ -0,0 +1,83 @@
+using System;
+using System.Linq;
+using JetBrains.Annotations;
+using Robust.Shared.GameObjects.Systems;
+using Robust.Shared.Interfaces.GameObjects;
+using Content.Shared.GameObjects;
+
+namespace Content.Server.GameObjects.EntitySystems
+{
+    /// <summary>
+    /// This interface gives components behavior on getting destoyed.
+    /// </summary>
+    public interface IDestroyAct
+    {
+        /// <summary>
+        /// Called when object is destroyed
+        /// </summary>
+        void OnDestroy(DestructionEventArgs eventArgs);
+    }
+
+    public class DestructionEventArgs : EventArgs
+    {
+        public IEntity Owner { get; set; }
+        public bool IsSpawnWreck { get; set; }
+    }
+
+    public interface IExAct
+    {
+        /// <summary>
+        /// Called when explosion reaches the entity
+        /// </summary>
+        void OnExplosion(ExplosionEventArgs eventArgs);
+    }
+
+    public class ExplosionEventArgs : EventArgs
+    {
+        public IEntity Source { get; set; }
+        public IEntity Target { get; set; }
+        public ExplosionSeverity Severity { get; set; }
+    }
+
+    [UsedImplicitly]
+    public sealed class ActSystem : EntitySystem
+    {
+        public void HandleDestruction(IEntity owner, bool isWreck)
+        {
+            var eventArgs = new DestructionEventArgs
+            {
+                Owner = owner,
+                IsSpawnWreck = isWreck
+            };
+            var destroyActs = owner.GetAllComponents<IDestroyAct>().ToList();
+
+            foreach (var destroyAct in destroyActs)
+            {
+                destroyAct.OnDestroy(eventArgs);
+            }
+            owner.Delete();
+        }
+
+        public void HandleExplosion(IEntity source, IEntity target, ExplosionSeverity severity)
+        {
+            var eventArgs = new ExplosionEventArgs
+            {
+                Source = source,
+                Target = target,
+                Severity = severity
+            };
+            var exActs = target.GetAllComponents<IExAct>().ToList();
+
+            foreach (var exAct in exActs)
+            {
+                exAct.OnExplosion(eventArgs);
+            }
+        }
+    }
+    public enum ExplosionSeverity
+    {
+        Destruction,
+        Heavy,
+        Light,
+    }
+}