* Use our own BBitmapStringField implementation which also requires our
own BColumn implementation. This is just a visual improvement which makes
both the eventual partiton icon and device label indent with the outline
level of the list item
* when setting the Unmount menu item enabled state, check wether the
partition in question is the /boot volume and disallow unmounting.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@23845 a95241bf-73f2-0310-859d-f6bbb57e9c96