this uses our ✨new and improved✨ logo by default, but can be easily
changed by modifying `/public/logo.svg`. the svg is loaded only once
when the application starts, so any modifications to it after a
deployment are visible immediately.
thanks to the power of CSS and SVG being able to make use of it, custom
colour schemes still work too.
- Move main navigation into views/navigation
- Split guest navigation into seperate file
- Move main navigation partials into subfolder
- Further adjustments for Bootstrap 4 compatibility