When we have windows on two different spaces and the user switches between them by
clicking our Dock icon, Cocoa inexplicably sends the switched-to window to the
back of the z-order.  It's only -makeKeyAndOrderFront: that brings it forward
again, but our override broke that.

This avoids adjusting window levels.  It also avoid unnecessarily deinterleaving
the windows of this and other processes.

Making a window a child reorders it to be immediately above or below its parent,
potentially undoing the ordering we had just done.

... rather than our orderedWineWindows array, which is going away.

This uses Cocoa and the window server to track windows and their z-order,
which is more reliable than our own tracking.