Added ability to allow external processing of the To/From/CC email list. r=mscott

mailnews/base/resources/content/msgHdrViewAddresses.js

@@ -38,4 +38,8 @@ function AddExtraAddressProcessing(emailAddress, addressButton)
 // message is loaded in message pane, we'll call this function...
 function NotifyClearAddresses()
 {
+}
+
+function FinishEmailProcessing()
+{
 }

mailnews/base/resources/content/msgHdrViewOverlay.js

@@ -348,7 +348,7 @@ function OutputEmailAddresses(parentBox, defaultParentDiv, emailAddresses, inclu
     {
       optionalToggleButton.removeAttribute('hideNonBox');
     }
-
+    FinishEmailProcessing();
   } // if msgheader parser
 }