Add new preference field to restrict usage of alternative templates for the view action

A new preference (in xwiki.cfg and in the XWiki.XWikiPreferences) should be added in "Advanced" to limit the "xpage" parameter used in the "view" action (when the right is "view"). The default list should be:

view, rdf, code

Using another template should require the "edit" right. This modification should be done in the rights system. A code review should be made to make sure that we won't break existing behavior with templates being used in non "edit" actions. The History link should be limited to users with the "edit" right.