o.a.x.p.DateEditor.toObjectImpl throws exception when date format is in different locale than the default one

There's the expanded-env-entries sample that uses a date in Locale.US format with DateFormat.MEDIUM style. It didn't run well on Polish locale (pl) and XBean's org.apache.xbean.propertyeditor.DateEditorTest.testToObjectImpl kept throwing "java.text.ParseException: Unparseable date: "Mar 1, 1954"" exception.

Attached is a patch for it. I'm not happy with it (I think it might've been written better), so I haven't applied it to the repo, but rather attach it here for others to look at it and correct where applicable.

p.s. The "Unreleased Versions" contains 3.1 which should be 3.2, I guess.