Add support for custom version

[groenroos]

• Add support for a new RAYGUN_VERSION global constant for overriding the default version (WP Core version)
• Supersedes Add filter for version #46
• Closes Ability to override version #43

[TheRealAgentK]

Could we add a defensive (string) cast on the constant value?

define() accepts any scalar, so someone writing define('RAYGUN_VERSION', 1.0) or define('RAYGUN_VERSION', 2) would probably trigger a TypeError here.

Suggested change:

function rg4wp_version(): string {
    static $version = null;
    if ($version === null) {
        $version = defined('RAYGUN_VERSION') ? (string) RAYGUN_VERSION : get_bloginfo('version');
    }
    return $version;
}

[TheRealAgentK]

Is this a potential XSS together with its usage further down around lines 80ish?

You could instead do:

$script .= 'rg4js("setVersion", ' . wp_json_encode(rg4wp_version()) . ');' . "\n";

[TheRealAgentK]

See comment above for context

If you append it to the script code after encoding it, then this line would become:

printf($script, get_option('rg4wp_apikey'));

[TheRealAgentK]

Thx for the PR @groenroos - added a few suggestions for hardening it a bit.