This commit changes the shebang in all shell scripts from absolute
paths (such as `/bin/bash` or `/usr/bin/python3`) to the `/usr/bin/env`
binary with the accompanying interpreter as it's argument.
The reason for this are as follows:
- NixOS cannot work with absolute paths
- BSD systems install their packages in /usr/local/bin
This removes the last cargo audit override (for the unmaintained
ansi_term).
Don't mark options as required when they have default values:
see <https://github.com/clap-rs/clap/pull/3793>.
As per #309
Update all references. There is one remaining hit for
git-grep '\.sh\b'
namely "build.sh" in maint/reproducible_build, which I think is
the build script for osxcross - ie, an external project.