Rework statusbar:

-Add sidebar on/off button
-Add sidebar places/tree toggle buttons
-Move zoom controls from main toolbar to slider in bottom right corner
-Place old statusbar centered in the new status toolbar

-Make sidebar on/off state a window-level toggle (instead of application-level)
-Make sidebar places/tree state a window-level toggle (instead of application-level)
Merge pull request #111 from mtwebster/tree-toggle

Rework statusbar