Implement user permission roles

[tdewolff]

Instead of a permission level use permission roles to more accurately allow/disallow users from parts of the site.

These roles for the admin area would be useful:

• Pages and assets and modules (editor)
• Settings and themes (settings)
• Moduler manager and template manager (manager)
• All (admin)
• User accounts (access)

[s-p-n]

I think permissions should be kept simple- simpler than roles even. It's possible for modules to add permissions, but I think the default permissions should only be "Editor" and "Administrator".

The editor can edit content. The administrator can do anything- including view the admin panel.

Again, third-party modules can extend the default permissions, adding subscribers or anything else.

[tdewolff]

Agreed, in retrospect I indeed see no need to make it more complex than two types of users. I would like to replace the dropdown in Edit User by radiobuttons then, and make sure it is extensible by modules.