add sigaction handler to Example Browser, to always shutdown shared memory

make GUI_SERVER more reliable
next attempt to connect to SHARED_MEMORY in Gym envs, if available, before DIRECT/GUI
allow software rendering fallback, even if ER_BULLET_HARDWARE_OPENGL is chosen in getCameraImage

examples/pybullet/gym/pybullet_envs/env_bases.py

@@ -82,7 +82,7 @@ class MJCFBaseBulletEnv(gym.Env):
 		(_, _, px, _, _) = p.getCameraImage(
 		width=self._render_width, height=self._render_height, viewMatrix=view_matrix,
 			projectionMatrix=proj_matrix,
-			#renderer=p.ER_BULLET_HARDWARE_OPENGL
+			renderer=p.ER_BULLET_HARDWARE_OPENGL
 			)
 		rgb_array = np.array(px)
 		rgb_array = rgb_array[:, :, :3]