Added a class to process command line arguments.

Currently, the class is very minimal. This was just to get the dump
argument working, so the parser wouldn't have to be involved in pushing
the lexer's output to terminal.
Minor changes to the lexer test file.
Edits to the CMakeLists.txt file to add in the Args class.
Two *very* minor edits to the Language Spec.
Changes to main.cpp to comply with coming changes in the Lexer.
Deleted code from the Parser.

The deleted code did output for the Lexer. It's now in the Lexer where
it belongs.
Changes to the Tokens to reflect new predeclared types and keywords.
Changes to lexer.h in preparation for changes in the Lexer.
Updates to the Lexer for new keywords and predeclared types.

These changes also put the Lexer output code in the Lexer. (It used to
be in the Parser.) The Lexer can now service three different modes:
stream, list, and dump.