Add to bookmarks leading to "The given key was not present in the dictionary"

[ForNeVeR]

Today, I've tried to right-click a tab in CyclopsChat and add a room to bookmarks, which led to a message being printed to the chat log:

Disconnect due 'The given key '\' was not present in the dictionary.'.

First of all, we should improve the error handling there, and also fix the issue.

TODO:

• [x] fix an issue with reconnection
• [ ] update SharpXMPP to a new version
• [x] fix the initial problem with rooms and keys