* BListItems now store the top offset of the frame within the parent BListView.
* This allows binary searching the clicked item.
* ItemFrame() is now a cheap call.
* Fixed several bugs in the sorting code of BOutlineListView which lead to
crashes of client applications.
* Implemented previously unimplemented functions in BOutlineListView.
git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@24092 a95241bf-73f2-0310-859d-f6bbb57e9c96