First tests for BTree
Pass BTreeTest.insertLeftRight
BTree: Refactor
BTree: Refactor
BTree: Refactor
BTree: Cleanup
Pass BTreeTest.insertRightRight
BTree: Refactor
BTree: Refactor
BTree: Refactor to optimize performance
BTree: Refactor
BTree: Add convenience methods
BTree: Remove dead code
Pass BTreeTest.split
BTree: Don't allocate node pointers for leaf nodes