parser: fix range of valid hex chars

js/parser.pegjs

@@ -23,7 +23,7 @@ number         = n:(hex / float / integer) {
                      return smalltalk.ValueNode._new()
                             ._value_(n)
                  }
-hex            = neg:[-]? "16r" num:[0-9a-zA-Z]+ {return parseInt((neg + num.join("")), 16)}
+hex            = neg:[-]? "16r" num:[0-9a-fA-F]+ {return parseInt((neg + num.join("")), 16)}
 float          = neg:[-]?int:[0-9]+ "." dec:[0-9]+ {return parseFloat((neg + int.join("") + "." + dec.join("")), 10)}
 integer        = neg:[-]?digits:[0-9]+ {return (parseInt(neg+digits.join(""), 10))}
 literalArray   = "#(" ws lits:(lit:literal ws {return lit._value()})* ws ")" {