XE-1418: Synchronize XWikiPreferences in the subwiki UI.

(cherry picked from commit 69af0639d206f88faba414cb295e219c103affb8)
XE-1418: Synchronize XWikiPreferences in the subwiki UI.

* Fix some problems introduced by the previous commit:
** Re-enabling the custom displayers.
** Re-setting the parent page.
** Re-setting the "undelete" right
** Removing the "programming" right. It should not be given on subwikis and I don't think it really works.

(cherry picked from commit 2513e899f7ee8142cb453ebd7b8d3c535fb17747)