Taskbar auto-hide when maximized v1.1 (#1193)

* Most code was rewritten, and the mod works in a slightly different way now - instead of switching auto-hide on and off, it's always left on, but the mod prevents the taskbar from hiding in certain conditions. That has benefits like a smoother transition between the states.
* The taskbar now auto-hides when a window intersects it. This can be disabled in the options.
* Auto-hiding can be suppressed altogether in the settings. In this case, maximized windows will be covered by the taskbar. This might be desirable if the taskbar is mostly transparent.