BUGFIX-66

Bug 26: Attempting To Reroot A Tree

This binary search tree algorithm allows single-pass, top-down treap key insertion.
Each node has two links (lt is short for less than, gt is short for greater than) and a key.
The code takes as input a single node (to) and a binary search tree with zero or more nodes (from).
Initially, to is the binary search tree produced by inserting key k1 into an empty tree.
Similarly, from is produced by inserting keys k2, k3, ..., kn (in that order) into an empty tree.
Afterward, to is the tree produced by inserting k1, k2, k3, ..., kn (in that order) into an empty tree.