Add support for ZNC buffer playback
Simplify and make message highlighting consistent

Remove the unnecessary intermediate signals and drop term 'alerted'
Forward any notices sent before RPL_WELCOME to the server view

AUTH/IP_LOOKUP etc.
SessionTree: do not swap the badge colors for selected items
SessionTree: delay badge reset
Fix MainWindow::closeTreeItem()
SessionTreeDelegate: badge font size take #2
Ctrl+S keyboard shortcut to switch to most active window