Added header utility/metaoperators.hpp, to automate the definition of
lexicographical comparisons in structures;
Added lexicographical comparisons to class Token (the comparison ignore position);
Added unit test to the Token comparison operators;
Restored test/main.test.cpp;
Modified makefile to make both a.out and test/test by default and run
the tests on `make test`;
Corrected recipe to clean and veryclean targets in makefile;
Corrected typos in ast.h.