allow floats and alpha-dashing operators.

c/mul/main.c

	mpca_lang(MPC_LANG_DEFAULT,
		"\
number   : /-?[0-9]+/ ; \
operator : '+' | '-' | '*' | '/' ; \
number   : /-?[0-9]+(\\.[0-9]+)?/ ; \
operator : '+' | '-' | '*' | '/' | /[a-zA-Z-]+/ ; \
expr     : <number> | '(' <operator> <expr>+ ')' ; \
lang     : /^/ <expr>+ /$/ ; \
",