Skip the tests which test for urlencoding, and add a TODO
in matrixService.

Webclient room data restructure

This works for both live and paginated events. Each 'message' event has
an associated '__room_member' key which points to the state of the sender
at that point in time. Invites have an additional key '__target_room_member'
which point to the state of the invitee at that point in time. This obviates
the need for mapping user_ids to *current* displaynames in the message list,
though this is still required for the user/presence list.

Reference the room_member key on messages which adjusts for current vs old_room_state. This displays names for historical users correctly, but is off by one (referencing content not prev_content).

Everything now uses modelService, but there are still one or two
minor teething problems to fix.

This breaks functionality whilst both events.rooms and modelService
are in use.