Fix the following bugs: - delete function incorrectly transplant the replacing node in the left threaded binary tree.
0.5.2
Fix the following bugs: - `get_height` functions did not check if the node is `None` in threaded binary trees - non-recursive in-order, reversed in-order, and post-order functions did not cover the case that we travel on the right side of the tree.
0.5.1
Added `Metrics` module for measuring trees' behavior and performance.