Support '* foo branch' entries.
Support '* foo branch' entries.

* tools/dist/backport.pl
  (sanitize_branch): New helper.
  (parse_entry): Use new helper and recognize '* foo branch' header lines.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion