LJ::join_community — Makes a user join a community. Takes care of all reluser relationships and friend stuff.
LJ::join_community(uuserid, ucommid, friend, noauto
uuserid. a userid or u object of the user doing the joining
ucommid. a userid or u object of the community being joined
friend. 1 to add this comm to user's friends list, else not
noauto. if defined, 1 adds P edge, 0 does not; else, base on community postlevel