Put "Media Only" option in column settings instead of content area headline (#7801)
* Action/reducer for changing column settings takes a path and a value
instead of a javascript object
* Settings menu version and column headline version working simultaneously
* remove column headline entirely
* remove css for headlines that aren't possible now
* Remove commented out code from unfruitful attempt at this feature
* Give direct timeline its own column settings bc it doesn't have a media only option
* Fix typo in public timeline code that was preventing per-column settings from working properly
* Fix codeclimate issues
* Missing semicolons
* Use redux state to set onlyMedia, let that do the update instead of a callback. Consequently, unpinned setting works without history modification
* Unused import