Merge branch 'polyline_track_tool' into jgrpp

# Conflicts:
#	src/rail_cmd.cpp
#	src/rail_gui.cpp
#	src/viewport.cpp
#	src/viewport_func.h

src/widgets/rail_widget.h

@@ -21,6 +21,7 @@ enum RailToolbarWidgets {
 	WID_RAT_BUILD_EW,       ///< Build rail along the game view X axis.
 	WID_RAT_BUILD_Y,        ///< Build rail along the game grid Y axis.
 	WID_RAT_AUTORAIL,       ///< Autorail tool.
+	WID_RAT_POLYRAIL,       ///< Polyline rail tool.
 	WID_RAT_DEMOLISH,       ///< Destroy something with dynamite!
 	WID_RAT_BUILD_DEPOT,    ///< Build a depot.
 	WID_RAT_BUILD_WAYPOINT, ///< Build a waypoint.