This part was approved (I think) previously but sending it out with
version synced to v18. Also, the name changed from "debug method" to
"xmethod". Hence, I think another review is required.

ChangeLog
2014-05-23  Siva Chandra Reddy  <sivachandra@google.com>

        * NEWS (Python Scripting): Add entry about the new xmethods
        feature.

        doc/
        *  python.texi (Xmethods In Python, XMethod API)
        (Writing an Xmethod): New nodes.
        (Python API): New menu entries "Xmethods In Python",
        "Xmethod API", "Writing an Xmethod".