PathPlanning/InformedRRTStar/informed_rrt_star.py: Fix hard coded graph axis (#982)

- Use self.min_rand, self.max_rand variable values in place of -2, 15

Author: wltjr

PathPlanning/InformedRRTStar/informed_rrt_star.py

@@ -293,7 +293,7 @@ def draw_graph(self, x_center=None, c_best=None, c_min=None, e_theta=None,
 
         plt.plot(self.start.x, self.start.y, "xr")
         plt.plot(self.goal.x, self.goal.y, "xr")
-        plt.axis([-2, 15, -2, 15])
+        plt.axis([self.min_rand, self.max_rand, self.min_rand, self.max_rand])
         plt.grid(True)
         plt.pause(0.01)