Implement basic chat functionality

assets/robocraft/chat.json

@@ -0,0 +1,18 @@
+{
+    "commands": [
+        {
+            "regex": "\\?online",
+            "op": {
+                "type": "BuiltIn",
+                "built_in": "OnlineUsers"
+            }
+        },
+        {
+            "regex": "\\?users",
+            "op": {
+                "type": "BuiltIn",
+                "built_in": "TotalUsers"
+            }
+        }
+    ]
+}