[pro] Make it possible to define the license key in wp-config.php

Hi there! I just bought a Professional (Lifetime) license of media cleaner pro. One feature I couldn’t find is the possibility to store the plugin’s license key in my wp-config.php. That’s how I do it for other premium plugins I use, like ACF or Relevanssi:

/**
 * Premium plugin keys
 */
define('ACF_PRO_LICENSE', 'XXXXXXX');
define('RELEVANSSI_API_KEY', 'XXXXXXX');

That would make it much easier to set-up this plugin on various sites, as well as in development/staging/production environments.

I know that I could probably use the filter pre_option_{optionname} to overwrite the key on the fly, but that’s a hacky solution and would make the key end up in my version control.

Could you implement something like the above?