Summary: Now you can actually replace an image! Ref T3572. This ended up needing a wee bit of infrastructure to work... - add replace image transaction to pholio - add replacesImagePHID to PholioImage - tweaks to editor to properly update images with respect to replacement - add edges to track replacement - expose getNodes on graph query infrastructure to query the entire graph of who replaced who - move pholio image to new phid infrastructure Still TODO - the history view should get chopped out a bit from the current view - no more inline comments / generally less functionality plus maybe a tweak or two to make this more sensical. Test Plan: replaced images and played with history controller a little. works okay. Reviewers: epriestley Reviewed By: epriestley CC: aran, Korvin Maniphest Tasks: T3572 Differential Revision: https://secure.phabricator.com/D6560