Rewrite the parser again, this time for good.

10_compiler_i_syntax_analysis/jackcompiler/syntax/parser.py
	-Finish iterating on the `parser` implementation after e030860
	and 5475cd5.
	-Settle on a object-oriented approach for constructing grammar
	rules (with the `GrammarRule` class), which improves type
	handling and makes the addition of new rules cleaner and less
	error-prone.