Add project navigator shortcode

[Anamon]

Articles that are part of a project should display an information box showing information on the project, the place of the current article, and navigational links.

• A project article infobox shortcode has to be available to project article pages.
  • The infobox must show the project the article belongs to.
  • The infobox must show which part of the project the current article represents.
  • The infobox must provide links to the previous and next article in the project series.
  • The infobox must provide a link to the project's overview page.
• It must be possible to place the infobox conveniently at the top of the article, possibly to the side.
• It should be possible to place several infoboxes alongside each other reasonably well, as each article may form part of multiple projects.
• The infobox must support internationalisation.