Add interface XMLTagEncoder.

Signed-off-by: yushijinhun <yushijinhun@gmail.com>
Merge branch 'nbt-collection' into xml
Add getExpansionProperty() method.

Signed-off-by: yushijinhun <yushijinhun@gmail.com>
Add DefaultXMLTagEncoder.

Signed-off-by: yushijinhun <yushijinhun@gmail.com>
Merge branch 'xml' into develop