Draft: merge federation branches and tons of changes picked from upstream
This is based on the set of changes @n0emis has collected and n0emis and me have run on our test servers for a while. it does also contain the experimental federation branch (inluding) and the front-fixed-url-config branch.
Marked as Draft: because I'm unclear if this should become "develop" or stay a separate branch, please discuss.
Edited by sknebel