Change color of marker for initial position

So we can better distinguish initial position from small islands on
the map.

Trajectories/plot_traj.py

@@ -29,7 +29,7 @@ def plot_single_traj(traj, e_overestim, SHPC, orientation, ax, src_crs,
                      annotate_flag, color):
     x, y = get_extr_coord(traj, e_overestim, SHPC, orientation)
     ax.plot(x, y, color, linewidth = 0.5, transform = src_crs)
-    ax.plot(x[0], y[0], marker = "s", markersize = 2, color = "black",
+    ax.plot(x[0], y[0], marker = "s", markersize = 2, color = "green",
             transform = src_crs)
 
     if annotate_flag: