Show machine-readable permission names on overview

Custom Permissions automatically creates a machine name for each permission, avoiding needless complexity, with config_perms_generate_machine_name(), a simple function doing no more and no less than this:

strtolower(preg_replace('/[^a-zA-Z0-9_]+/', '_', $string))

This opens up the opportunity to use Sentence casing for the default permissions provided by Custom Permissions, but to keep it easy to use these permissions in code, the machine name form should be exposed for all saved permissions. (Since Drupal core does not extend this courtesy on the main permissions page.)

Open to patches or to arguing to leave well enough alone.