User preferences

[sbrl]

Different users have different preferences - that much is obvious. Currently Pepperminty Wiki is don't event have a system in place for storing this kind of information, let alone an interface! We really ought to do something about this as part of #69.

• [x] Alter $settings->users to have an object per user instead of a string containing their password
• [x] Expose the new $settings->users structure through $env
  • [x] Add the ability to easily re-save the user's preferences (this will make it easy for modules to update them and store arbitrary data that's attached to the logged in user)
• [x] Add the ability for a user to change their password
• [x] Optionally store the user's email in here too
• [x] Start looking at #107
• [x] Build a GUI for the user preferences created above

[sbrl]

Thats the email address saving done! We should add a simple verification code system to it at some point.

[sbrl]

Done, along with avatars! :fireworks: :balloon: :smiley_cat: