Federation for v3/v4 rooms (#954)

* Update gomatrixserverlib

* Default to room version 4

* Update gomatrixserverlib

* Limit prev_events and auth_events

* Fix auth_events, prev_events

* Fix linter issues

* Update gomatrixserverlib

* Fix getState

* Update sytest-whitelist

* Squashed commit of the following:

commit 067b875063
Author: Neil Alexander <neilalexander@users.noreply.github.com>
Date:   Fri Apr 3 14:29:06 2020 +0100

    Invites v2 endpoint (#952)

    * Start converting v1 invite endpoint to v2

    * Update gomatrixserverlib

    * Early federationsender code for sending invites

    * Sending invites sorta happens now

    * Populate invite request with stripped state

    * Remodel a bit, don't reflect received invites

    * Handle invite_room_state

    * Handle room versions a bit better

    * Update gomatrixserverlib

    * Tweak order in destinationQueue.next

    * Revert check in processMessage

    * Tweak federation sender destination queue code a bit

    * Add comments

commit 955244c092
Author: Ben B <benne@klimlive.de>
Date:   Fri Apr 3 12:40:50 2020 +0200

    use custom http client instead of the http DefaultClient (#823)

    This commit replaces the default client from the http lib with a custom one.
    The previously used default client doesn't come with a timeout. This could cause
    unwanted locks.
    That solution chosen here creates a http client in the base component dendrite
    with a constant timeout of 30 seconds. If it should be necessary to overwrite
    this, we could include the timeout in the dendrite configuration.
    Here it would be a good idea to extend the type "Address" by a timeout and
    create an http client for each service.

    Closes #820

    Signed-off-by: Benedikt Bongartz <benne@klimlive.de>

    Co-authored-by: Kegsay <kegan@matrix.org>

* Update sytest-whitelist, sytest-blacklist

* Update go.mod/go.sum

* Add some error wrapping for debug

* Add a NOTSPEC to common/events.go

* Perform state resolution at send_join

* Set default room version to v2 again

* Tweak GetCapabilities

* Add comments to ResolveConflictsAdhoc

* Update sytest-blacklist

* go mod tidy

* Update sytest-whitelist, sytest-blacklist

* Update versions

* Updates from review comments

* Update sytest-blacklist, sytest-whitelist

* Check room versions compatible at make_join, add some comments, update gomatrixserverlib, other tweaks

* Set default room version back to v2

* Update gomatrixserverlib, sytest-whitelist

roomserver/version/version.go

@@ -43,12 +43,12 @@ var roomVersions = map[gomatrixserverlib.RoomVersion]RoomVersionDescription{
 		Stable:    true,
 	},
 	gomatrixserverlib.RoomVersionV3: RoomVersionDescription{
-		Supported: false,
-		Stable:    false,
+		Supported: true,
+		Stable:    true,
 	},
 	gomatrixserverlib.RoomVersionV4: RoomVersionDescription{
-		Supported: false,
-		Stable:    false,
+		Supported: true,
+		Stable:    true,
 	},
 	gomatrixserverlib.RoomVersionV5: RoomVersionDescription{
 		Supported: false,