Cleanup MessageHandler::getReceiver()
Move the waitForDisconnected() hack to ~Session()
TextBrowser: delay setting the document upon first show event
TextBrowser: avoid document relayouting while hidden
UserListView: delay user list sorting upon first show
MainWindow: establish stored connections right away
Adapt to IrcTextFormat::toHtml()
TextBrowser: revert some of the recent optimizations

It was too hostile to delay setting the document upon first show
event and to keep everything in a buffer while hidden. It resulted
to noticeable flicker for views being shown for the first time, and
also auto scrolling becoming unreliable.
MessageFormatter::formatSender(): <strong> -> <b>
Added a view search popup
Revise shortcuts

Ctrl+S => "search" view by name
Ctrl+L => switch to most "lively" view
Revamp shortcut configuration
ShortcutWizard: show "Cmd" instead of "Ctrl" on Mac
Rename MessageHandler to SessionModel
Add Server/Channel/QueryItem for SessionModel
SessionModel: take Server/Channel/QueryItem's in use

MessageReceiver is gone!
Add ChannelItem::topic
Reorganize: add model/ subdir
Reorganize: move SortedUserModel within gui/
Reorganize: shared/ -> util/