Renamed FeatureType.characteristics as FeatureType.properties for conformance with common usage
(I'm not sure that ISO 19109 "characteristics" was exactly the same thing, since ISO seems to use
"characteristics" in a broader sense than "properties"). Also provide better check about whether
a property overrides a property of the super-type, and whether is overriding is legal.


git-svn-id: https://svn.apache.org/repos/asf/sis/branches/JDK8@1594544 13f79535-47bb-0310-9956-ffa450edef68