Drop an unimplemented method in Group

We didn't need it for years, so let's remove it and if we
really need it, it's easy to add again.

SVN_SILENT

events.cpp

@@ -1661,8 +1661,6 @@ bool Group::groupEvent(XEvent* e)
 {
     unsigned long dirty[ 2 ];
     leader_info->event(e, dirty, 2);   // pass through the NET stuff
-    if ((dirty[ WinInfo::PROTOCOLS ] & NET::WMIcon) != 0)
-        getIcons();
     if ((dirty[ WinInfo::PROTOCOLS2 ] & NET::WM2StartupId) != 0)
         startupIdChanged();
     return false;

group.cpp

@@ -319,11 +319,6 @@ void Group::lostLeader()
     }
 }
 
-void Group::getIcons()
-{
-    // TODO - also needs adding the flag to NETWinInfo
-}
-
 //***************************************
 // Workspace
 //***************************************

group.h

@@ -58,7 +58,6 @@ public:
     void deref();
     EffectWindowGroupImpl* effectGroup();
 private:
-    void getIcons();
     void startupIdChanged();
     ClientList _members;
     Client* leader_client;