Remove shebang line when not strictly required

Summary: The shebang line `#!<path to interpreter>` is only required for Python scripts, so remove it on source files for class or function definitions. Additionally explicitly mark as executable the actual Python scripts in the codebase.

Reviewed By: nikhilaravi

Differential Revision: D20095778

fbshipit-source-id: d312599fba485e978a243292f88a180d71e1b55a

docs/tutorials/utils/camera_visualisation.py

@@ -1,4 +1,3 @@
-#!/usr/bin/env python3
 # Copyright (c) Facebook, Inc. and its affiliates. All rights reserved.
 
 import matplotlib.pyplot as plt

docs/tutorials/utils/plot_image_grid.py

@@ -1,4 +1,3 @@
-#!/usr/bin/env python3
 # Copyright (c) Facebook, Inc. and its affiliates. All rights reserved.
 
 import matplotlib.pyplot as plt