Part of #9744
Removes all redundant `# -*- coding: utf-8 -*-` lines from files, as python 3 automatically reads source code as utf-8 now.
`Signed-off-by: Jonathan de Jong <jonathan@automatia.nl>`
Builds on the work done in #9643 to add a federation API for space summaries.
There's a bit of refactoring of the existing client-server code first, to avoid too much duplication.
