TYPO3 Core

I would like to have one place for a pagetree (= a page with is_siteroot and subpages) where I can define
- the base URL for this site
- what the mighty "sys_language=0" means for this pagetree
- what languages are available for this pagetree (and how they are overlaid)

Once this is defined, we can easily
- resolve the information in the FE via a PSR-15 middleware and a Site object and a RequestContext object
- create absolute URLs for a page (in CLI, BE and FE)
- remove TypoScript options (FE only) and bring them in a Site object containing all this information, also available for BE