Changes to Wikit Revision History between r12 and r13

Small patch to enable revision history to be stored in the Wikit TKD file.

This has only been tested with the CGI interface.

'''Cumulative Patches'''
   * http://www.rkeene.org/projects/info/resources/projects/wikit/revisions/wikit-revs-1rsk.diff
   * http://www.rkeene.org/projects/info/resources/projects/wikit/revisions/wikit-revs-2rsk.diff
   * http://www.rkeene.org/projects/info/resources/projects/wikit/revisions/wikit-revs-3rsk.diff
   * http://www.rkeene.org/projects/info/resources/projects/wikit/revisions/wikit-revs-4rsk.diff
   * http://www.rkeene.org/projects/info/resources/projects/wikit/revisions/wikit-revs-5rsk.diff
   * http://www.rkeene.org/projects/info/resources/projects/wikit/revisions/wikit-revs-6rsk.diff
(blank line)
   * http://www.rkeene.org/projects/info/resources/projects/wikit/revisions/wikit-revs-7rsk.diff
(blank line)
'''Incremental Patches'''
   * http://www.rkeene.org/projects/info/resources/projects/wikit/revisions/wikit-revs-3_to_4rsk.diff
   * http://www.rkeene.org/projects/info/resources/projects/wikit/revisions/wikit-revs-4_to_5rsk.diff
   * http://www.rkeene.org/projects/info/resources/projects/wikit/revisions/wikit-revs-5_to_6rsk.diff
   * http://www.rkeene.org/projects/info/resources/projects/wikit/revisions/wikit-revs-6_to_7rsk.diff

Legend

     Only in r12
     Only in r13
     -->      Modified slightly between r12 and r13