Fixes bug #1332438: PNS router crashes when you another track while routing in "shove" mode

pcbnew/router/pns_joint.h

@@ -112,7 +112,7 @@ public:
         LINKED_ITEMS::iterator f = std::find( m_linkedItems.begin(), m_linkedItems.end(), aItem );
 
         if( f != m_linkedItems.end() )
-            m_linkedItems.erase( f );
+            f = m_linkedItems.erase( f );
 
         return m_linkedItems.size() == 0;
     }

pcbnew/router/pns_node.cpp

@@ -1216,14 +1216,21 @@ int PNS_NODE::FindByMarker( int aMarker, PNS_ITEMSET& aItems )
 
 int PNS_NODE::RemoveByMarker( int aMarker )
 {
+    std::list<PNS_ITEM*> garbage;
+
     for( PNS_INDEX::ITEM_SET::iterator i = m_index->begin(); i != m_index->end(); ++i )
     {
         if ( (*i)->Marker() & aMarker )
         {
-            Remove( *i );
+            garbage.push_back( *i );
         }
     }
 
+    for( std::list<PNS_ITEM*>::const_iterator i = garbage.begin(), end = garbage.end(); i != end; ++i )
+	{
+        Remove( *i );
+    }
+
     return 0;
 }