Optionally show unmounted disks as grayed out along with mounted disks

[jonas.kirilla]

I would like to have the option to show unmounted disks along with the mounted ones, on the desktop and in the Disks folder, as grayed out items.

Opening one such unmounted volume would mount it, normalize its icon colors, and open its window. Closing its windows would leave it mounted.

Mounted and unmounted volumes should be listed in the on-disk order, same as in the mount menu, unless the user has rearranged them. (In which case Tracker would need to keep track of the placement of non-BFS volumes by some other means than how it is currently done for BFS-volumes.)

[waddlesplash]

Moving Tracker enhancement tickets out of R1 milestone -- Tracker's source code comes from BeOS R5, so it already has all the features it did on R5.