Some changes to KPartition, KDiskDevice, KDiskSystem on this way.
Still missing is KPartition::Publish() and its invocation in
KDiskDeviceManager. Then everything should be in place to start with
porting the scanning parts of our disk system modules.
git-svn-id: file:///srv/svn/repos/haiku/trunk/current@3486 a95241bf-73f2-0310-859d-f6bbb57e9c96