Add a function to add leafs to the tree at any level
Add type information to certain node operations, not thought-out yet
Describe the new tree implementation in comments at the top of ztree.c
Make experimental changes, check Linux for memory errors
Get rudimentary test_new_tree working, valgrind-safe here
Fix a valgrind error, not initializing child nodes on split
Try a solution for creating intermediate nodes in-line with traversal
Add a ztree_next_sibling function, reimplement the ztree_next function
Change add_leaf function to require_node and specify its behavior
Remove some out-dated functions
Add a save/load function to the ztree-test file
Make a few aesthetic changes