jaxb2-plugins: metadata plugin refactoring, class/instance-level descriptors

Signed-off-by: Ketoth Xupack <ketoth.xupack@gmail.com>
jaxb2-plugins: metadata plugin support for validation plugin

Signed-off-by: Ketoth Xupack <ketoth.xupack@gmail.com>
jaxb2-plugins: naming fixes

Signed-off-by: Ketoth Xupack <ketoth.xupack@gmail.com>
typetools: style

Signed-off-by: Ketoth Xupack <ketoth.xupack@gmail.com>
jaxb2-plugins: generated methods should be excluded from normal jaxb processing

Signed-off-by: Ketoth Xupack <ketoth.xupack@gmail.com>