Pcbnew: connect.cpp: enhanced ( faster and more powerful ) algorithm to...

Pcbnew: connect.cpp: enhanced ( faster and more powerful ) algorithm to calculate connections between pads.
Code cleaning.

pcbnew/class_track.h

@@ -61,8 +61,8 @@ protected:
     int         m_Drill;            // for vias: via drill (- 1 for default value)
 
 public:
-    BOARD_ITEM* start;              // pointers to a connected item (pad or track)
-    BOARD_ITEM* end;
+    BOARD_CONNECTED_ITEM* start;    // pointers to a connected item (pad or track)
+    BOARD_CONNECTED_ITEM* end;
     std::vector<TRACK*> m_TracksConnected;   // list of other tracks connected to me
 
     int         m_Param;            // Auxiliary variable ( used in some computations )

pcbnew/editrack.cpp

@@ -994,7 +994,7 @@ void DeleteNullTrackSegments( BOARD* pcb, DLIST<TRACK>& aTrackList )
     TRACK*      firsttrack = track;
     TRACK*      oldtrack;
 
-    BOARD_ITEM* LockPoint = track->start;
+    BOARD_CONNECTED_ITEM* LockPoint = track->start;
 
     while( track != NULL )
     {