Don't assume location of bash

Not all environments (NixOS, for example) put bash in /bin. It's more portable to use
`/usr/bin/env bash`, which looks up the location of bash dynamically. In
practice the location of the env command is fairly standardized.

Author: RocketPuppy

argsparse-completion.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # -*- tab-width: 4; encoding: utf-8; -*-
 #
 #########

argsparse.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 # -*- tab-width: 4; encoding: utf-8; -*-
 #
 #########

tutorial/0-completion

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 tutorial_directory=${BASH_SOURCE[0]%/*}
 

tutorial/1-basics

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 PATH="..:$PATH"
 

tutorial/2-values

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 #
 
 PATH="..:$PATH"

tutorial/3-cumulative-options

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 PATH="..:$PATH"
 

tutorial/4-types

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 PATH="..:$PATH"
 

tutorial/5-custom-types

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 PATH="..:$PATH"
 

tutorial/6-properties

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 PATH="..:$PATH"
 

tutorial/7-value-checking

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 PATH="..:$PATH"