contrib: update tcsh_completion for Mercurial 1.8
Added the following commands: bookmarks debugignore.
Fix the tcsh parse script for the current help text layout.
$echo'[Section]'>>$HGRCPATH$echo'KeY = Case Sensitive'>>$HGRCPATH$echo'key = lower case'>>$HGRCPATH$hgshowconfigSectionSection.KeY=CaseSensitiveSection.key=lowercase