Adds Handheld Radio/Listener system (#1457)

* re-do of old PR that got fuckied upp

* simplify foreach as suggested

* pass distance to PassSpeechData for a check, remove GetListenRange()

* adds RadioQuery instead of subscribing/unsubscribing

* change SpreadMessage to accept owner rather than component

* change RadioQuery to EntityQuery

* remove declared EntityQuery (oops, didn't know what shadowcommander meant)

* refactor ListeningSystem & refactor added chat logic into listen sys

* IGNORE the oopsie STOP LOOKING

Content.Server/GameObjects/EntitySystems/RadioSystem.cs

@@ -0,0 +1,49 @@
+using Content.Server.GameObjects.Components.Interactable;
+using JetBrains.Annotations;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Robust.Shared.GameObjects;
+using Robust.Shared.GameObjects.Systems;
+using Robust.Shared.Interfaces.GameObjects;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace Content.Server.GameObjects.EntitySystems
+{
+    class RadioSystem : EntitySystem
+    {
+        private List<string> _messages;
+
+        public override void Initialize()
+        {
+            base.Initialize();
+
+            EntityQuery = new TypeEntityQuery(typeof(RadioComponent));
+            _messages = new List<string>();
+        }
+
+        public void SpreadMessage(IEntity source, string message)
+        {
+            if (_messages.Contains(message))
+            {
+                return;
+            }
+
+            _messages.Add(message);
+
+            foreach (var radioEntity in RelevantEntities)
+            {
+                var radio = radioEntity.GetComponent<RadioComponent>();
+                if (radioEntity == source || !radio.RadioOn)
+                {
+                    continue;
+                }
+
+                radio.Speaker(message);
+            }
+
+            _messages.Remove(message);
+        }
+    }
+}