* Implement gomatrixserverlib.HeaderedEvent, which should allow us to store room version headers along with the event across API boundaries and consumers/producers, and intercept unmarshalling to get the event structure right
* Add federationsender to previous
* Add wiring for querying the roomserver for the default room version
* Try to implement /capabilities for room versions
* Update copyright notices
* Update sytests, add /capabilities endpoint into CS API
* Update sytest-whitelist
* Add GetDefaultRoomVersion
* Fix cases where state package was shadowed
* Fix version formatting
* Update Dockerfile to Go 1.13.6
* oh yes types I remember
* And fix the default too
* Merge forward
* Tidy up a bit
* TODO: What to do with NextBatch here?
* Replace SyncPosition with PaginationToken throughout syncapi
* Fix PaginationTokens
* Fix lint errors
* Add a couple of missing functions into the syncapi external storage interface
* Some updates based on review comments from @babolivier
* Some updates based on review comments from @babolivier
* argh whitespacing
* Fix opentracing span
* Remove dead code
* Don't overshadow err (fix lint issue)
* Handle extremities after inserting event into topology
* Try insert event topology as ON CONFLICT DO NOTHING
* Prevent OOB error in addRoomDeltaToResponse
* Thwarted by gocyclo again
* Fix NewPaginationTokenFromString, define unit test for it
* Update pagination token test
* Update sytest-whitelist
* Hopefully fix some of the sync batch tokens
* Remove extraneous sync position func
* Revert to topology tokens in addRoomDeltaToResponse etc
* Fix typo
* Remove prevPDUPos as dead now that backwardTopologyPos is used instead
* Fix selectEventsWithEventIDsSQL
* Update sytest-blacklist
* Update sytest-whitelist
