A new tarball packages the source for local building instead of a
pre-built binary. This enables installing on architectures other than
x86.

The launchd.plist bundled with Invert Catalina Invert assumes that the
binary is installed in `/usr/local/bin/`. However, since Homebrew's
support for Apple Silicon, the default install directory can be either
`/opt/homebrew/` or `/usr/local/` on Intel Macs.

Generate the launchd.plist in the Homebrew formula to allow us to always
get the correct Homebrew prefix path.

Now that we don't have a `.undent` method, we need to use `~`.

Remove `undent` call, which apparently is no longer implemented
according to this error message:

    Error: undefined method `undent' for #<String:0x000000014fd17590>
    Did you mean?  undef
                   indent
                   indent!
    /opt/homebrew/Library/Taps/teddywing/homebrew-formulae/HomebrewFormula/qcd.rb:16:in `caveats'
    /opt/homebrew/Library/Homebrew/caveats.rb:23:in `caveats'
    /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/forwardable.rb:224:in `empty?'
    /opt/homebrew/Library/Homebrew/formula_installer.rb:777:in `caveats'
    /opt/homebrew/Library/Homebrew/formula_installer.rb:836:in `finish'
    /opt/homebrew/Library/Homebrew/upgrade.rb:209:in `install_formula'
    /opt/homebrew/Library/Homebrew/install.rb:327:in `install_formula'
    /opt/homebrew/Library/Homebrew/install.rb:317:in `block in install_formulae'
    /opt/homebrew/Library/Homebrew/install.rb:316:in `each'
    /opt/homebrew/Library/Homebrew/install.rb:316:in `install_formulae'
    /opt/homebrew/Library/Homebrew/cmd/install.rb:222:in `install'
    /opt/homebrew/Library/Homebrew/brew.rb:93:in `<main>'

Also correct the following `brew audit` warnings:

    16: col 16: Place the first line of a multi-line method definition's body on its own line.
    25: col 1: `EOS` is not aligned with `def caveats; <<-EOS.undent`.

Running `brew audit` flagged a warning about this `version` line and
recommended removing it:

    $ brew audit --tap teddywing/formulae
    teddywing/formulae/dome-key:
      * Stable: version 1.0 is redundant with version scanned from URL

New taps were no longer possible with recent versions of Homebrew, as
their internal version APIs changed. On attempting to tap the
repository, the following error would prevent it:

    $ brew audit --tap teddywing/formulae
    Error: teddywing/formulae/dome-key: uninitialized constant OS::Mac::Version::SYMBOLS

Homebrew no longer has that identifier, and moved version numbers and
keys to a different class.

Remove the version check so that we don't depend on internal Homebrew
APIs which are liable to change at any time. Actually, knowing the
project, even the public APIs are liable to change at any time. And
since the `:lion` key hasn't existed in Homebrew for quite some time
now, it doesn't really make sense to have a programmatic check for Lion
since we have no way to check for it, and Homebrew doesn't support it
regardless.

The `PREFIX` variable in the Makefile was changed to `DESTDIR`.

The release tarball was updated to include a root directory.