message: cache setting where it's easy
diff: @@ -108,6 +108,7 @@ module.exports = React.createClass({
  },
  componentWillMount: function() {
  + this._editingEnabled = SettingsStore.isFeatureEnabled("feature_message_editing");
  // the event after which we put a visible unread marker on the last
  // render cycle; null if readMarkerVisible was false or the RM was
  // suppressed (eg because it was at the end of the timeline)
  @@ -576,7 +577,6 @@ module.exports = React.createClass({
  const scrollToken = mxEv.status ? undefined : eventId;
  const readReceipts = this._readReceiptsByEvent[eventId];
  - const editingEnabled = SettingsStore.isFeatureEnabled("feature_message_editing");
  ret.push(
  <li key={eventId}
  @@ -586,7 +586,7 @@ module.exports = React.createClass({
  <EventTile mxEvent={mxEv}
  continuation={continuation}
  isRedacted={mxEv.isRedacted()}
  - replacingEventId={editingEnabled && mxEv.replacingEventId()}
  + replacingEventId={this._editingEnabled && mxEv.replacingEventId()}
  editState={isEditing && this.props.editState}
  onHeightChanged={this._onHeightChanged}
  readReceipts={readReceipts}
  