Move InvalidXMLException into its own file

src/Danmichaelo/QuiteSimpleXMLElement/InvalidXMLException.php

@@ -0,0 +1,14 @@
+<?php
+
+namespace Danmichaelo\QuiteSimpleXMLElement;
+
+use Exception;
+use RuntimeException;
+
+class InvalidXMLException extends RuntimeException
+{
+    public function __construct($message = null, $code = 0, Exception $previous = null)
+    {
+        parent::__construct($message, $code, $previous);
+    }
+}

src/Danmichaelo/QuiteSimpleXMLElement/QuiteSimpleXMLElement.php

@@ -46,14 +46,6 @@
 use InvalidArgumentException;
 use SimpleXMLElement;
 
-class InvalidXMLException extends Exception
-{
-    public function __construct($message = null, $code = 0, Exception $previous = null)
-    {
-        parent::__construct($message, $code, $previous);
-    }
-}
-
 class QuiteSimpleXMLElement
 {
     public $namespaces;