Add rudimentary 'saveWorld' command in shared memory API and pybullet, see examples/pybullet/saveWorld.py

Use trilinear filtering instead of bilinear

examples/pybullet/saveWorld.py

@@ -0,0 +1,8 @@
+import pybullet as p
+import time
+
+p.connect(p.SHARED_MEMORY)
+timestr = time.strftime("%Y%m%d-%H%M%S")
+filename = "saveWorld" + timestr + ".py"
+p.saveWorld(filename)
+p.disconnect()