Role mixins / Subroles

Given you build something like a Drupal distribution containing of several submodules, for example managed via features, there is one major problems, how do you manage permissions.
Per default Drupal stores every permission of a given role in a single configuration. This makes it hard to have multiple features providing permissions. So for example a gallery feature would like to grant permissions to create images, and an article feature would like to grant permissions for editing articles.

The role mixin module allows to configure parent roles on roles. These parent roles then inherit the permissions of those sub roles.