Removed TODO marker for unimportant task of which it is also not
immediately clear how to implement it.
Removed obsolete TODO

I originally added this TODO to suggest a nick name when adding a new
chat room. However, in the mean time I have decided to not allow nick
changes upon joining a new chat room, so this solution is now obsolete.
Fixed bug where command without parameters would not be recognized.
Log exceptions caused by command execution and added markers for improvements.
Fix incorrect registration state in case user cancels IRC connection because of certificate issue.