Pattern matching is order-dependent

This is particularly bothersome when writing custom serializers. (Note the different order of the fields in each call to parse)

scala> val JObject(JField("test", JDouble(x)) :: JField("two", JString(s)) :: Nil)
     |   = parse("""{"test":3.0,"two":"three"}""")
x: Double = 3.0
s: String = three

scala> val JObject(JField("test", JDouble(x)) :: JField("two", JString(s)) :: Nil)
     |   = parse("""{"two":"three","test":3.0}""")
scala.MatchError: JObject(List((two,JString(three)), (test,JDouble(3.0))))
(of class org.json4s.JsonAST$JObject)
[...]

Start by reproducing the two parse examples in the issue and trace how JObject is matched against the field patterns. Confirm the behavior with an order-swapped object, then make the demonstrated destructuring work regardless of JSON field order and verify both examples succeed.