[Frontend-GNOME] Disable forced NotificationAreaIconMode.Closed mode for Ubuntu's Messaging Menu

As of Ubuntu 12.10's libmessaging-menu, Smuxi can no longer restore a
hidden (closed) main window from messaging menu, as it relies on
single-instance behavior/support of the application [0]. The messaging menu
simply launches the application desktop file and expects that the application
detects the already running instance and restores a hidden/closed main window.

As of now Smuxi does not support single-instance as IPC on Mono and Linux
simply sucks.

Here the path that leads to clone wars:
 * You start Smuxi from launcher
 * You close the Smuxi window with the "X" button -> launcher no longer believes Smuxi is still running
 * libmessaging-menu no longer allows to bring Smuxi back (as it did with libindicate)
 * launcher and messaging menu will both now start new instances when you activate Smuxi
 * You close Smuxi's main window again with the "X" button
 * You activate Smuxi from the messaging menu or launcher -> you spawn another clone

 [0]: https://bugs.launchpad.net/indicator-messages/+bug/1065732/comments/1
[Engine-XMPP] Fixed ArgumentNullException when joining MUCs with room messages (closes: #770)
Merge branch 'stable'
[Engine] Dont't trust Cygwin's "uname -o" on Windows
Merge pull request #11 from carlosmn/campfire
[Frontend-GNOME] Support replying to persons by clicking on their nickname in the message area (closes: #771)

There are nicknames that are either difficult to remember and/or to type
(e.g. me4oslav). For this reason the user is now able to click on a nickname
in the message area and Smuxi automatically types that nick into the entry box.

Thanks goes to Marcelo Hashimoto (@conscioususer) for this nice idea!
[Debian] Made libgio2.0-cil-dev an optional build-dep as lucid doesn't contain it
[Engine{,-XMPP,-IRC}] Removed leftover code that caused a crash when a contact with an uppercase letter in the nickname rejoined a xmpp muc.
[Engine-XMPP] Fixed Sync Problems occuring during muc join
[Engine-XMPP] Join a muc with a custom nickname of your choice (default is still username)
Merge pull request #12 from oli-obk/bugfix/xmpp_muc_crash
[Engine-XMPP] Fixes null Exception on receipt of presence updates without a Resource
Merge pull request #13 from oli-obk/bugfix/xmpp_presence_crash
[lib/jabber-net] Updated to send proper presence updates to muc
Merge pull request #14 from oli-obk/bugfix/xmpp_muc_presence
[Frontend-GNOME] Reference indicate-sharp instead of messagingmenu-sharp in .csproj
[Frontend-GNOME] Add 2 pixel padding in front of the entry box to avoid text-cursor not visible issue
[Build] Fixed build on Mono 3.0
[Frontend-GNOME] Updated author and artist credits
[Frontend-GNOME] Join bar follows current active network (closes: #780)