Added In-game GM handbook with !id command (#463)

* Added In-game GM handbook with !id command

* Removed unused import

src/tools/exceptions/IdTypeNotSupportedException.java

@@ -0,0 +1,11 @@
+package tools.exceptions;
+
+public class IdTypeNotSupportedException extends Exception {
+    public IdTypeNotSupportedException() {
+        super("The given ID type is not supported");
+    }
+
+    public IdTypeNotSupportedException(String message) {
+        super(message);
+    }
+}