Added a diagram of the lexer FSM and updated the parser grammar.
Various minor tweaks to the text.
Updated the discussion of the occurs-check to explain it more clearly and justify the decision to allow violating bindings.
Fixed tenses in the project overview.
Added a section under Preparation describing the code structure, which includes the discussion of the Prolog lexer/parser.
Moved the Unit Tester section from Implementation to Preparation.
Added a diagram for the Byrd box model.
Renamed Terms to ProTerms