Pneumatic cannons (#4560)

* basics & visuals

* pneumatic cannon works perf

* loc + popups

* gas tank does stuff + queue changes

* updates

* b

* forcefeeding

* inhand

* crafting!

* pie cannon now is a pneumatic cannon

* oopy

* fix for entman + verbs

* pie

* change for tools

* actual

* combat mode + better sounds

* reviews

Content.Shared/PneumaticCannon/SharedPneumaticCannon.cs

@@ -0,0 +1,18 @@
+using System;
+using Robust.Shared.Serialization;
+
+namespace Content.Shared.PneumaticCannon
+{
+    [Serializable, NetSerializable]
+    public enum PneumaticCannonVisualLayers : byte
+    {
+        Base,
+        Tank
+    }
+
+    [Serializable, NetSerializable]
+    public enum PneumaticCannonVisuals
+    {
+        Tank
+    }
+}