Adds MtHash and MtTree
MtHash is an array based implementation of a hash table. It borrows
heavily from HKL's implementation of HklHash.
MtTree is a red black tree based on the "Left Leaning Red Black Trees"
paper published by Robert Sedgewick.

This is laying the groundwork for definition support. Definitions
require a symbol table which will be provided by MtHash. MtHash uses
MtTree for collision handling.

MtTree probably wont be used elsewhere in marktab.