message: Fix improper splice when determining vias for tombstones
  `splice` takes one element from the array whereas `slice` takes all after a given point. We want `slice` so we can pick up ipv6 addresses and port numbers.
diff: @@ -370,7 +370,7 @@ export default class MessageComposer extends React.Component<IProps, IState> {
  if (createEvent && createEvent.getId()) createEventId = createEvent.getId();
  }
  - const viaServers = [this.state.tombstone.getSender().split(':').splice(1).join(':')];
  + const viaServers = [this.state.tombstone.getSender().split(':').slice(1).join(':')];
  dis.dispatch({
  action: 'view_room',
  highlighted: true,
  