fix(track): the tip of a blade is where the diverging track of the switch is broken into pieces near the start, as a template lays it from the scheme of the switch, so blades of 60E1 and 49E1 switches keep the cut tips of their tables at 1.248, 1.500, 2.165, 2.633 and 3.335 m and blades of S42 switches start at the end of their pre-blade stretch; without such a break a blade is told angled or tangent by its angle to the stock rail taken back to where it touches it, read from the nearest point of the other rail instead of its nearest sample, which took the blade of the main track of an S42-190-1:6,6 for a tangent one

world/Segment.h

@@ -123,6 +123,10 @@ public:
     std::size_t
         PieceCount() const {
             return m_pieces.size(); };
+    inline
+    double
+        PieceStart( std::size_t const Piece ) const {
+            return m_starts[ Piece ]; };
     double
         ComputeLength() const; // McZapkie-150503
     // finds point on segment closest to specified point in 3d space. returns: point on segment as value in range 0-1