updated rsnxsitems with discrete msgs and grp item rather than collection of msgs/grps
added flags header file
added first declaration of implemented genexchange service (client API interface)
git-svn-id: http://svn.code.sf.net/p/retroshare/code/branches/v0.5-new_cache_system@5180 b45a01b8-16f6-495d-af2f-9b41ad6348cc
