Use 'python3' instead of 'python' in hashbangs

It's not obligatory for distributions to have a 'python' binary these
days, but 'python3' is likely to be available:
https://www.python.org/dev/peps/pep-0394/#for-python-runtime-distributors.
Change all hashbangs to point to 'python3'.

This will break running

    $ ./script.py

on *nix systems that don't have a 'python3' executable. Changing it to

    $ python script.py

is pretty painless at least.

This change won't break Python 2 when installing via 'pip', because
entry_points creates bounce scripts with their own hashbangs.

The major version will be increased, in case someone looks at the major
version but doesn't install via 'pip'.

Fixes: #89

alldefconfig.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright (c) 2018-2019, Ulf Magnusson
 # SPDX-License-Identifier: ISC

allmodconfig.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright (c) 2018-2019, Ulf Magnusson
 # SPDX-License-Identifier: ISC

allnoconfig.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright (c) 2018-2019, Ulf Magnusson
 # SPDX-License-Identifier: ISC

allyesconfig.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright (c) 2018-2019, Ulf Magnusson
 # SPDX-License-Identifier: ISC

defconfig.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright (c) 2019, Ulf Magnusson
 # SPDX-License-Identifier: ISC

examples/menuconfig_example.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Implements a simple configuration interface on top of Kconfiglib to
 # demonstrate concepts for building a menuconfig-like. Emulates how the

examples/merge_config.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # This script functions similarly to scripts/kconfig/merge_config.sh from the
 # kernel tree, merging multiple configurations fragments to produce a complete

genconfig.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright (c) 2018-2019, Ulf Magnusson
 # SPDX-License-Identifier: ISC

guiconfig.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright (c) 2019, Ulf Magnusson
 # SPDX-License-Identifier: ISC

listnewconfig.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright (c) 2018-2019, Ulf Magnusson
 # SPDX-License-Identifier: ISC

menuconfig.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright (c) 2018-2019, Nordic Semiconductor ASA and Ulf Magnusson
 # SPDX-License-Identifier: ISC

oldconfig.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright (c) 2018-2019, Ulf Magnusson
 # SPDX-License-Identifier: ISC

olddefconfig.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright (c) 2018-2019, Ulf Magnusson
 # SPDX-License-Identifier: ISC

savedefconfig.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright (c) 2019, Ulf Magnusson
 # SPDX-License-Identifier: ISC

setconfig.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 # Copyright (c) 2019, Ulf Magnusson
 # SPDX-License-Identifier: ISC