Party and friends

This branch is a work in progress to introduce Party system in roBrowser
Here a brief todo list :

- [x] Display friends (online/offline status).
- [x] Can add friends using right click context.
- [x] Can remove friend from UI.
- [x] Lock function enable.
- [ ] Add support for /hi command.
- [ ] Display "Friend" in private messages.
- [x] Display Party members.
- [x] Add support for offline/online/leader icons.
- [x] Display party members location.
- [x] Display party members life.
- [ ] Able to create team from UI.
- [ ] Able to create team from command (/organize).
- [x] Able to invite players (from context menu).
- [ ] Able to invite players from UI.
- [ ] Able to invite players from command (/invite).
- [x] Able to leave the party from UI.
- [x] Able to leave the party from command (/leave).
- [x] Able to expel members from UI (and right click on UI).
- [x] Able to change leader.
- [ ] Display Party setup window.
- [ ] Resizable window.
- [ ] Save window position.
- [ ] Execute skill on party members directly on the UI.