Configuration Overhaul plan

This will not work out. A site currently is a request attribute, and depends on either of the two things:

  1. The selected page in the page tree (a site is connected the root page of a subtree)
  2. The current URI (a site is also connected to a base URI)

Therefore the current site will never be injectable via DI (unless we do some globals hackery, which we aim to get rid of)