Introducing @partysharelvl, a method to updating the party share level in run time!
- Temporarily changes share level until character server is restarted
- Updated atcommands documentation

git-svn-id: https://rathena.svn.sourceforge.net/svnroot/rathena/trunk@17358 54d463be-8e91-2dee-dedb-b68131a5f0ec