Add Name.getSeparator() to simplify use of Name interface

The Name interface is targeted as a replacement for the Java QName interface that works with full namespace (rather than a prefix) in order to qualify a "local" name.

The Name interface currently does not define how the namespace and localPart are to be combined when displayed to the user; as such we are in a strange conflict where:

• we want namespace to be as simple as possible
• we want namepace + locaPart to look like a normal URI

We want to prevent the motivation for including a "separator" in the namespaceURI; We also want to make sure that the namespaceURI is available for implementors to use without any extra processing (the danger with including a separator in the namespace would be the code required to remove it prior to using the string for lookup).

As an example http://www.opengis.net/gml#AbstractFeatureCollectionBaseType

To prevent this we want to add a Name.getSeparator().

We need to be clear that equality and hashcode is based on the namespace and the localPart only.