No longer try to parse a generic type if there's no possible candidates

[metoule]

With the current algorithm that parses known types, we first try to parse the type argument list before checking if there's a matching generic type definition in the known types. This leads to an improper error message when trying to perform a less than comparison on a unknown identifier, because we try to parse the comparison as the type argument list 😅

var i = new Interpreter();
var x= i.Eval("b < 1"); // ParseException: '>' expected (at index 4). [misleading]

Fix #314

[davideicardi]

🙏