(svn r12252) -Fix [FS#1801]: Broken FollowTrack_t related functions (thanks michi_cc).

-Fixed by removing FollowTrack_t structure and all related functions. Their purpose was to allow to call track followers from C code. They were:
  1. never used
  2. obsoleted by switching to C++

src/yapf/follow_track.hpp

@@ -7,12 +7,32 @@
 
 #include "yapf.hpp"
 
+
 /** Track follower helper template class (can serve pathfinders and vehicle
  *  controllers). See 6 different typedefs below for 3 different transport
  *  types w/ of w/o 90-deg turns allowed */
 template <TransportType Ttr_type_, bool T90deg_turns_allowed_ = true>
-struct CFollowTrackT : public FollowTrack_t
+struct CFollowTrackT
 {
+	enum ErrorCode {
+		EC_NONE,
+		EC_OWNER,
+		EC_RAIL_TYPE,
+		EC_90DEG,
+		EC_NO_WAY,
+	};
+
+	const Vehicle*      m_veh;           ///< moving vehicle
+	TileIndex           m_old_tile;      ///< the origin (vehicle moved from) before move
+	Trackdir            m_old_td;        ///< the trackdir (the vehicle was on) before move
+	TileIndex           m_new_tile;      ///< the new tile (the vehicle has entered)
+	TrackdirBits        m_new_td_bits;   ///< the new set of available trackdirs
+	DiagDirection       m_exitdir;       ///< exit direction (leaving the old tile)
+	bool                m_is_tunnel;     ///< last turn passed tunnel
+	bool                m_is_bridge;     ///< last turn passed bridge ramp
+	bool                m_is_station;    ///< last turn passed station
+	int                 m_tiles_skipped; ///< number of skipped tunnel or station tiles
+	ErrorCode           m_err;
 	CPerformanceTimer* m_pPerf;
 
 	FORCEINLINE CFollowTrackT(const Vehicle* v = NULL, CPerformanceTimer* pPerf = NULL)