ADDED: typechecking
ADDED: CCCCCCC: Childish and Critically Challenged Compiler for C-minus Crafted by Chen
ADDED: types from section A.2 of Appendix A from the textbook
ADDED: syntax rules
ADDED: a copy of source code in C-minus for testing usage
FIXED: relop/addop/mulop in syntax specification ccccccc.y