Merged revisions 1605821, 1605823 from tomcat/trunk:
Refactoring with a view to adding transformation (i.e. extension) support to outgoing messages.
Extract MessagePart into standalone class


git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1625464 13f79535-47bb-0310-9956-ffa450edef68
Merged revisions 1605890,1605891 from tomcat/trunk:
- Fix an i18n TODO
- This time with the unsupported extension name


git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1625466 13f79535-47bb-0310-9956-ffa450edef68