* removing "client" package.
* minor update to the test suite.
* +javadoc on ZMessage object.
* changed some builder-method names in the ZMessage.
* minor update to ZMessageTest.
* changed package name "channel" to "io".
* +support of socket_identity in the ZSocketFactory.
* tests covering router/req and router/dealer AND newly added support of socket_identity.
* minor improvements in the ZBaseSocketFactory.
* corrected java docs here-and-there.