s patch makes the concept of maximum and minimum size of the panel

actually meaningful:
the idea is that an applet can change its own preferred size and ask its
containment if it can fullfill its wish on the size
so the panel tries to resize itself as it can in its maximum and minimum
size constraints.
at the moment only the taskbar uses this, also the systray could use it
(and in general all expanding applets)
it use a new signal in Plasma::Applet, called
sizeHintChanged(Qt::SizeHint)

svn path=/trunk/KDE/kdebase/workspace/libs/plasma/; revision=838364

applet.h

@@ -511,6 +511,11 @@ class PLASMA_EXPORT Applet : public QGraphicsWidget
          * can coordinate themselves with these changes if they desire.
          */
         void geometryChanged();
+        
+        /**
+         * Emitted by Applet subclasses when they change a sizeHint and wants to announce the change
+         */
+        void sizeHintChanged(Qt::SizeHint which);
 
         /**
          * Emitted when an applet has changed values in its configuration