[Azoth Acetamide] implement ICLEntry::MarkMsgsRead() (bug #1556)
[Azoth Acetamide] implement ICLEntry::ChatTabClosed()
[Azoth Acetamide] remove unread messages and doesn't use chattabclosable
Merge pull request #318 from Maledictus/acetamide_#1556

Acetamide #1556