Add emacs-bzr-version

* lisp/version.el (emacs-bzr-get-version): New function.
* lisp/loadup.el (emacs-bzr-version): Set it. 
* lisp/mail/emacsbug.el (report-emacs-bug): Include bzr version.

* etc/NEWS: Mention this, though it is not really relevant to releases.
Insert template for 24.2 release.

Fixes: debbugs:8054

lisp/loadup.el

@@ -259,6 +259,8 @@
 	   (versions (mapcar (function (lambda (name)
 					 (string-to-number (substring name (length base)))))
 			     files)))
+      (setq emacs-bzr-version (condition-case nil (emacs-bzr-get-version)
+                              (error nil)))
       ;; `emacs-version' is a constant, so we shouldn't change it with `setq'.
       (defconst emacs-version
 	(format "%s.%d"