Re-apply fixes to the link-email screen to make it work again (in a somewhat temporary way until home servers sign associations). Unhide the linked emails box.

BF: Do not filter incoming member events. Before, only invitations to the current user  were showned in the recents.

Conflicts:
	CHANGES.rst

Don't do auth for change_membership in federation handler, it doesn't work and federation doesn't do auth in general either. Add a hacky timeout when trying to join a remote room.

Needed to split into 2 conditional spans for grammar reason

Conflicts:
	synapse/http/client.py

Add support for registering with a threepid to the HS (get credentials from the client and check them against an ID server).

Normalise users power levels so that the user with the higher power level will have a bar covering 100% of the width of his avatar