Frontend-GNOME: allow wrapping to first/last from last/first chat

This restores the behavior of with tabs which allowed wrapping from the last tab
to the first tab and from the last tab to the first tab.
git-contributors: don't count merge commits
Frontend: populate CMD* hook variables for command-manager hooks
Merge branch 'stable'
Engine: added CMD_CHARACTER to command hook environment
Merge branch 'stable'
Engine-IRC: added translator hint for "Queuing joins" msg string
Engine-IRC: fixed already joined detection of /join command (closes: #921)
Frontend: fixed potential NRE with commands issued from command hooks
Engine-JabbR: fixed potential NRE in CommandHelp() when issued from hooks

CommandModel.FrontendManager is null when issued from hooks
Engine-Twitter: fixed generating duplicate [01] short id (closes: #912)
Merge branch 'stable'
Engine: implemented ProtocolManagerBase.ToString()
Engine: also scan for protocol managers in smuxi-engine.dll
Engine: also check name when looking up protocols
[Engine-VBulletinChatbox] Initial vBulletin Chatbox support.

Initial protocol module for the vBulletin Chatbox plugin.
[Engine-VBulletinChatbox] Fix skipping old messages.
[Engine-VBulletinChatbox] Leave message parsing to MessageBuilder.
[Engine] Use HtmlAgilityPack to parse HTML and improve image parsing.
[Engine-VBulletinChatbox] Implement /me support.