Moving css into /css, for organizational purposes.
Moving away from VirtualDocumentRoot again, as it was simply not acceptable for me to have to change .htaccess for each project.
Big rework of the default vhost, which now also automatically manages Apache's vhosts.

* A vhost file gets written automatically for each new directory under www/, just visiting a domain for the first time will automatically cause Apache to be reconfigured and the user to be redirected.
* Unified css/js/img and other assets under www/default/assets and symlinking to it.
* Using composer to manage dependencies.
* Under templates/ we can now easily edit output, without touching PHP.
* All code, including our own, is now PSR-4 compliant and decoupled.