Lexer: remove redundant case for ?.

Author: antonmedv

parser/lexer/state.go

@@ -32,7 +32,7 @@ func root(l *lexer) stateFn {
 		l.emit(Bracket)
 	case strings.ContainsRune(")]}", r):
 		l.emit(Bracket)
-	case strings.ContainsRune("#,?:%+-^", r): // single rune operator
+	case strings.ContainsRune("#,:%+-^", r): // single rune operator
 		l.emit(Operator)
 	case strings.ContainsRune("&|!=*<>", r): // possible double rune operator
 		l.accept("&|=*")