Added package GetSetting method (ref #166).
Added disabling View menu for non-existing panes.
Updated settings restore to activate Output pane and set focus on the editor.
Added support for joining/splitting Watch/Stack with Output/Console tabs.
Added dragging Watch/Stack tabs out of docked panes.
Updated Watch/Stack tabs to refresh only when shown.
Updated Watch/Stack tabs to refresh when they get focus.
Fixed dragging tabs out of split notebooks.
Added workaround for combined windows after dragging a tab on top of active tab.
Merge branch 'dockable-stack-watch-tabs'
Added activation of windows with SDL_app class name (Moai support).