Feature Request: Generalize names of default permission levels

[Griatch]

Description of requested feature:

Rename the default permission levels to names that better describe their function in the context of Evennia. The current permission levels are:

• Immortals
• Wizards
• Builders
• Player Helpers
• Players

The suggested new default permission hierarchy would be:

• Developers
• Admins
• Builders
• Helpers
• Players

Reasons for adding feature:

The Immortals/Wizard levels are highly steeped in MUD history but just what they do is not obvious to someone from outside Evennia. For example, "Wizard" is the highest-level permission for many game servers and Immortals/Wizards are used interchangeably for others. In (default) Evennia, the Immortals are those with server control and Python access (Devs) while Wizards can kick people and manage the user base (Admins). the new names reflect this more naturally. Changing Player Helpers to just Helpers also makes this tier more generic as a mid-point between Players and a full-on Builder.

Extra information

This change requires data migrations and belongs in a dev branch leading up to Evennia 0.7.

[Griatch]

Closed with the merger of devel branch.