napen123

I believe rewriting the parser to use the [shunting-yard algorithm](https://en.wikipedia.org/wiki/Shunting-yard_algorithm) is something we should look into. The current way we parse input can do so reasonably well, but it's lacking...

This fails to parse, with _System.FormatException: Input string was not in a correct format_ being thrown: ```csharp MathParser parser = new MathParser(); parser.Operators.Add("λ", (left, right) => Math.Pow(left, right)); Assert.AreEqual(Math.Pow(3, 2),...