Merge: Nitiwiki next

Some fixes for nitiwiki in prevision for the nitlanguage.org site migration and the resolution of #824.

Do not consider b481cea since it belongs to #1368 (and break the loader)

Feature summary:
* ini accept array notation
* customizable sidebar content
* customizable sidebar position
* wikilinks support external links
* better search by title
* better search by path
* make breadcrumbs and summaries optionnal
* add link to github for last_changes and edit mode

Pull-Request: #1444
Reviewed-by: Lucas Bajolet <r4pass@hotmail.com>
Reviewed-by: Jean Privat <jean@pryen.org>