refactored random subsystem

added compile-time seed support

grid/walk/GridWalkPushForward.h

@@ -8,6 +8,7 @@
 #include "../Grid.h"
 
 #include "../../math/DrawList.h"
+#include "../../math/Random.h"
 #include "../../nav/dijkstra/Dijkstra.h"
 
 #include "GridWalkState.h"
@@ -31,7 +32,7 @@ private:
 	static constexpr float HEADING_ALLOWED_SIGMA = Angle::degToRad(20);
 
 	/** fast random-number-generator */
-	std::minstd_rand gen;
+	RandomGenerator gen;
 
 	/** 0-mean normal distribution */
 	std::normal_distribution<float> headingChangeDist = std::normal_distribution<float>(0.0, HEADING_CHANGE_SIGMA);