Implemented a preliminary disk device scanning in KDiskDeviceManager.

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

headers/private/kernel/disk_device_manager/KDiskSystem.h

@@ -26,6 +26,7 @@ public:
 	virtual bool IsFileSystem() const;
 	bool IsPartitioningSystem() const;
 
+	// manager will be locked
 	status_t Load();		// load/unload -- can be nested
 	void Unload();			//
 	bool IsLoaded() const;