lexer can now read single character tokens

src/token/token.hpp

@@ -8,5 +8,9 @@ namespace token {
     struct token {
         ::token::type type;
         std::string literal;
+
+        token(::token::type t, std::string s): type(t), literal(s) {}
+
+        token(::token::type t, char c): type(t), literal(1, c) {}
     };
 } // namespace token