Overhauled data access layer to support new model:
- Changed Item.getParent to Item.getCollections() to get ids of parent collections
- Removed Item.setPosition() -- item positions are set internally when items are added to and deleted from collections, but the orderIndex is not currently used or manipulatable externally
- Item constructor/Items.getNewItemByType()/Items.add() no longer take folderID and orderIndex as parameters
- Split getTreeRows() into Scholar.getCollections(parent) and Scholar.getItems(parent), which return root collections or all library items, respectively, if no parent given
- All references to folders in object/method/property names changed to collections
- New methods Collection.addItem(itemID), Collection.hasItem(itemID), Collection.removeItem(itemID)
- Collection.erase() takes optional deleteItems parameter to delete items from DB -- otherwise just removes association and leaves item in library (does, however, delete all descendent collections from DB regardless)
* Note: This will break displaying of items until interface code is updated. *
