More sane next batch handling, typing notification tweaks, give invites their own stream position, device list fix (#1641)

* Update sync responses

* Fix positions, add ApplyUpdates

* Fix MarshalText as non-pointer, PrevBatch is optional

* Increment by number of read receipts

* Merge branch 'master' into neilalexander/devicelist

* Tweak typing

* Include keyserver position tweak

* Fix typing next position in all cases

* Tweaks

* Fix typo

* Tweaks, restore StreamingToken.MarshalText which somehow went missing?

* Rely on positions from notifier rather than manually advancing them

* Revert "Rely on positions from notifier rather than manually advancing them"

This reverts commit 53112a62cc3bfd9989acab518e69eeb27938117a.

* Give invites their own position, fix other things

* Fix test

* Fix invites maybe

* Un-whitelist tests that look to be genuinely wrong

* Use real receipt positions

* Ensure send-to-device uses real positions too

syncapi/sync/notifier_test.go

@@ -335,7 +335,7 @@ func waitForEvents(n *Notifier, req syncRequest) (types.StreamingToken, error) {
 		return types.StreamingToken{}, fmt.Errorf(
 			"waitForEvents timed out waiting for %s (pos=%v)", req.device.UserID, req.since,
 		)
-	case <-listener.GetNotifyChannel(*req.since):
+	case <-listener.GetNotifyChannel(req.since):
 		p := listener.GetSyncPosition()
 		return p, nil
 	}
@@ -365,7 +365,7 @@ func newTestSyncRequest(userID, deviceID string, since types.StreamingToken) syn
 			ID:     deviceID,
 		},
 		timeout:       1 * time.Minute,
-		since:         &since,
+		since:         since,
 		wantFullState: false,
 		limit:         DefaultTimelineLimit,
 		log:           util.GetLogger(context.TODO()),