new walker (control+path)

added new sanity checks
fixed minor errors
added corresponding test-cases
added moving-median

grid/walk/GridWalkLightAtTheEndOfTheTunnel.h

@@ -46,6 +46,8 @@ public:
 	/** ctor with the target you want to reach */
 	template <typename Access> GridWalkLightAtTheEndOfTheTunnel(Grid<T>& grid, const Access& acc, const T& target) {
 
+		gen.seed(1234);
+
 		// build all shortest path to reach th target
 		dijkstra.build(target, target, acc);