Binary Balanced Search Tree. Simple code with recursion.
This is a fork of JuYanYan/AA-Tree, then modified to use STRUCT data structures, each in its own tree.
It requires each structure to begin with NODE declaration, so saves a data pointer, and makes code a library where any declared struct can be used and retrieved without extra code. It changes so that there is a TREE structure which contains the root node and subroutines for print and compare to allow different sturctures to be handled in same code