Cleanup useless IrcSessionPrivate::_irc_reconnect()
Add IrcProtocol
IrcMessage: limit parent type to IrcSession*

IrcMessage needs access to the IrcSession in order to initialize
the flags and stuff (own msg, caps etc.) properly so the parent
will be from now on limited to IrcSession*.
Cleanup IrcMessage
Add IrcMessage::fromParameters()
communi.prf: ditch qtAddLibrary() - no longer works for qt5
Merge branch 'master' of https://github.com/communi/communi into quazaa-compatibility
communi.prf: respect COMMUNI_INSTALL_XXX
Merge branch 'master' of https://github.com/communi/communi into quazaa-compatibility