This an in memory C# B+ Tree implementation. A BTree might be faster but I want to eventually make a disk based version.
And B+ trees seem to be recommended for that situation.
It is an alternative to binary search trees like treap, AA, red-black and AVL trees.

It is complete as far as an IDictionary<TKey, TValue> implementation.
It does not have the Cursor implemented yet for moving to a key and then going forward or backward
It uses about 1/3 the memory of a Dictionary which is good but takes 5 times as long to do add, remove or lookup data which is bad.
But items are maintained in sorted order unlike a hash table.