Add IronPython 2.7.4 to project

docs/Credits.aml

@@ -103,6 +103,14 @@
 </externalLink>
   </para></listItem>
   
+  <listItem><para>
+  <externalLink>
+<linkText>IronPython</linkText>
+<linkAlternateText>Used for the Python shell/integration in the UI.</linkAlternateText>
+<linkUri>http://ironpython.net/</linkUri>
+</externalLink>
+  </para></listItem>
+  
   <listItem><para>
   <externalLink>
 <linkText>Sandcastle Help File Builder</linkText>