fixed tons of small issues with keyboard focus on game mode when tabbing between object list and object property panels. tab/shift-tab cycles focus between these and the running game so you can play and tune seamlessly. a panel's titlebar visual changes when it doesn't have focus.
see "Code simplification for bind commands" trello card - added PulldownMenuItem.art_mode_allowed and game_mode_allowed, so that the "is app in game mode" checks can be removed from various art mode command functions, replaced with checks for allowed flags vs current mode.
fixed a bug introduced by session saving. now we restore session (loading arts for edit) before loading game state, else the art edit renderables will be super goofed up when they get loaded for edit from game mode.
Renderable.move_to cleanup and clarity; bug in previous item wasn't due to this but investigation led me across it.
added Art.get_simple_name for debug logging uses
fixed issue #55 - reposition art renderables when active one changes size
fixed issue #56 - tab/shift-tab move forward and backward, respectively, through dialog fields
fix a few uncommong-repro input focus issues, egclicking buttons with a dialog open