Dockable CAD level Toolbar

Create a dockable box for turning CAD Levels on/off, Just Like the Probe Readout is dockable.

I do think the Probe Readout window dock should span multiple toolbar lines instead of pushing toolbars onto separate line. For instance. If all of your toolbars are on the left half of the top of the screen, the probe readout should be able to sit next to them without pushing down toolbars below it. Same things for a CAD Level Dock.