Moved org.apache.sis.io.wkt from the sis-referencing module to the sis-metadata one,
in order to allow us to use it with identifiers. This is because the WKT 2 syntax is
slightly more complex than the WKT 1, so it may be worth to define ImmutableObject
as a FormattableObject subclass for letting it do its job itself.


git-svn-id: https://svn.apache.org/repos/asf/sis/branches/JDK7@1564821 13f79535-47bb-0310-9956-ffa450edef68