PHP 8.0 Support

[arcticlinux]

I've just been doing some preliminary testing with PHP 8. I didn't test everything but the only thing stopping me from running in PHP 8 with how I'm using Halite was that MB_OVERLOAD_STRING was removed in 8.0.

paragonie/sodium_compat/src/Core/Util.php:915

((int) (ini_get('mbstring.func_overload')) & MB_OVERLOAD_STRING);

I just defined that constant for my rather limited testing.

if (!defined('MB_OVERLOAD_STRING')) {
    define('MB_OVERLOAD_STRING', 2);
}

[paragonie-security]

This is a sodium_compat issue, not a Halite issue, but we'll fix it upstream.

[paragonie-security]

paragonie/sodium_compat@13a6155

[arcticlinux]

The only other thing was in composer.json, but that has been resolved as well.

[spaze]

PHP 8 throws a warning when using final private, #158