Search the web with selected text.

Add context menu option when selecting text in order to search the web for the selection.
The url used in web search configurable in the ChatView settings panel.
Uses the zoom-in icon until it gets it's own icon.
Use a different icon for web search
Improve reliability of SSL connections

First, this fixes a bug similar to Bug #1249 except for SSL
connections.  If the TCP connection fails but isn't
actually closed before the SSL handshake is complete,
Quassel will become stuck and never attempt to reconnect.
The solution is to start the ping timeout even earlier,
before the connection is established at all.

Second, this fixes the issue where multiple presses of the
"Disconnect" button and long waits were required to close
certain broken SSL connections (where SSL negotiation was
not yet complete, as above).  The solution is to call
socket.abort() instead of socket.disconnectFromHost(),
which will ensure that the socket is closed immediately.
Additionally, in case that fails for some reason, the
socketCloseTimer is no longer a single-shot timer, so
if the first abort doesn't work, it will keep trying.

(Probably?) fixes bug #1005
set SO_KEEPALIVE on client sockets
Socket options require Qt 4.6+
Implement issue #1219: Update the marker line when quassel loses focus

Solves issue #1219 on bugs.quassel-irc.org.

We now listen for QEvent::WindowDeactivate in the main window. This
should pickup on window closing/minimizing/losing focus. We also change
view->setMarkerLine() to Client::setMarkerLine which will send an event
to the syncher, and eventually arrives at ChatView::markerLineSet, which
moves the marker line for us.
Update AboutDlg