GitLab

add external project link in post infos, replace link in project title

* I forgot to add the cover-related stuff in the ProjectsManager's functions
* I forgot a comma in the sql query in AdminManager

*add preload for 404.css

*add output buffering
*add preload for font & minified.css

*optimize icon.png, mobile-menu-icon & mobile-menu-icon-close.png, and serveur_petit.png
*remove ubuntu-related fonts, now the site use sans-serif and a subset of share tech mono

* titles of articles & projects are now centered
* they also have a background color

*update adminview design (take all width available)
*update blog posts & projects without cover views (same width as posts with cover)
*update menu (underline is now more thick)