Several changes: (1) Add number of unreachable markers in experiment state. (2) Have GUI update icons and text to reflect this new information. (3) Update the GUI to a near-finished state, removing a ton of buttons and functionality that won't be needed for the user study. (4) Have the session send state pushes every 1/2 second to keep the GUI fresh (otherwise icons / text don't update until actions switched). (5) Cache reachability so that we're not sending thousands of IK solver requests, which allows the app to function while still sending the reachability semi-frequently.