Rehashing wikis

[Matthew East]

Pruning:

* consolidated various pages into one page: HelpOnEditing. Thus the
following pages are obsolete and I will delete them if nobody objects:
DocumentHowTo, HelpOnFormatting, HelpOnHeadings, HelpOnLinking,
HelpOnLists, HelpOnTables.

* Reparented and Linked HelpOnEditing to WikiTips, away from a userpage.

* Link on FrontPage to DocumentHowTo changed to HelpOnEditing

* A few references in various pages added to emphasise that preferred
markup is MoinMoin. HelpPage is still weak on this.

The intention of this was to render it easier for users to learn about
the wiki and consequently contribute more. As always, please tell me if
you disagree with any changes.