Frontend-GNOME-XMPP: AddChatState function name did not represent what the function does
Engine(-XMPP),Frontend-GNOME-XMPP: offline/away/available messages don't make much sense in private chats

added PresenceStateAway and PresenceStateOffline to be able to filter them in the frontend and display as presence states instead (only one presence state is ever displayed). PresenceStateOnline removes all chat and presence states.
Merge pull request #135 from oli-obk/feature/offline_away_chatstates
Common: don't run uname on Windows

Windows usually has no uname except Cygwin or GNUwin is installed and in %PATH%.
This led to annoying DOS windows on startup of Smuxi.
Merge branch 'stable'
Engine(-XMPP), Frontend-GNOME: updating a tab's title was not possible, but required for xmpp person chats

previously this was done by removing the chat and adding a new one