BETA: Added two new methods and updating JavaDocs:
	* `public L2PcInstance getRandomPartyMember(L2PcInstance player, L2Npc npc)`
	* `public boolean checkPartyMember(L2PcInstance player, L2Npc npc)`
Patch by: jurchiks
Reviewed by: Adry_85, UnAfraid, Nos

git-svn-id: http://svn.l2jserver.com/branches/unstable/L2J_Server_BETA@6321 d34dfa0f-f91c-0410-86dd-cf06f19dd0ad