Narrow down collector

RTree keeps track of position as well.  We can use this to reduce the
amount of time spent in the collector routine

eeschema/ee_collectors.cpp

@@ -152,9 +152,11 @@ void EE_COLLECTOR::Collect( SCH_SCREEN* aScreen, const KICAD_T aFilterList[], co
         bool sheetsVisited = false;
         bool globalLabelsVisited = false;
 
-        for( const KICAD_T* filter = aFilterList; *filter != EOT; ++filter )
+        EE_RTREE& items = aScreen->Items();
+
+        for( const KICAD_T *filter = aFilterList; *filter != EOT; ++filter )
         {
-            for( SCH_ITEM* item : aScreen->Items().OfType( *filter ) )
+            for( SCH_ITEM *item : items.Overlapping( *filter, aPos, m_Threshold ) )
             {
                 if( *filter == SCH_SYMBOL_T || *filter == SCH_LOCATE_ANY_T )
                     symbolsVisited = true;
@@ -171,19 +173,19 @@ void EE_COLLECTOR::Collect( SCH_SCREEN* aScreen, const KICAD_T aFilterList[], co
 
         if( !symbolsVisited )
         {
-            for( SCH_ITEM* item : aScreen->Items().OfType( SCH_SYMBOL_T ) )
+            for( SCH_ITEM *item : items.Overlapping( SCH_SYMBOL_T, aPos, m_Threshold ) )
                 item->Visit( m_inspector, nullptr, m_scanTypes );
         }
 
         if( !sheetsVisited )
         {
-            for( SCH_ITEM* item : aScreen->Items().OfType( SCH_SHEET_T ) )
+            for( SCH_ITEM *item : items.Overlapping( SCH_SHEET_T, aPos, m_Threshold ) )
                 item->Visit( m_inspector, nullptr, m_scanTypes );
         }
 
         if( !globalLabelsVisited )
         {
-            for( SCH_ITEM* item : aScreen->Items().OfType( SCH_GLOBAL_LABEL_T ) )
+            for( SCH_ITEM *item : items.Overlapping( SCH_GLOBAL_LABEL_T, aPos, m_Threshold ) )
                 item->Visit( m_inspector, nullptr, m_scanTypes );
         }
     }