Parse unary question mark operator

Lexer/PureTokenFactory.cs

@@ -58,7 +58,7 @@
             "+", // UnaryPlus = 57,
             "-", // UnaryMinus = 58,
             "~", // UnaryNot = 59,
-
+            "?", // UnaryQuestionMark = 60,
         };
         
         public PureToken CreatePunctuation(TokenKind kind)

Lexer/TokenKind.cs

@@ -50,5 +50,6 @@
         UnaryPlus = 57,
         UnaryMinus = 58,
         UnaryNot = 59,
+        UnaryQuestionMark = 60,
     }
 }

Parser/MParser.cs

@@ -495,6 +495,7 @@ namespace Parser
                 case TokenKind.Plus:
                 case TokenKind.Minus:
                 case TokenKind.Not:
+                case TokenKind.QuestionMark:
                     return true;
                 default:
                     return false;
@@ -549,6 +550,8 @@ namespace Parser
                     return TokenKind.UnaryMinus;
                 case TokenKind.Not:
                     return TokenKind.UnaryNot;
+                case TokenKind.QuestionMark:
+                    return TokenKind.UnaryQuestionMark;
                 default:
                     throw new ArgumentException(nameof(kind));
             }