Window shortcuts now toggle (raise/minimize) windows.

This allows me to use all applications in a Yakuake-like method.
I can define a shortcut for an application, press it, window shows up, do my work, press it again and it hides.
This is specifically good for a Text Editor<-->Browser switching workflow.
Also my first kwin patch.

activation.cpp

@@ -922,6 +922,10 @@ void Client::updateUrgency()
 
 void Client::shortcutActivated()
 {
+    Client* raised_client = workspace()->topClientOnDesktop(desktop(), -1);
+    if (isActive() && this == raised_client) // if client is already raised, pressing its shorcut hides it, giving the shortcut a 'toggle' effect
+        setMinimized(true);
+    else
         workspace()->activateClient(this, true);   // force
 }