Make it possible to sign up as lexicographer on homepage

[kolatubosun]

Currently, we have to create 'users' on the dashboard, and give them privileges to be able to contribute to the dashboard as lexicographers. It's time we make it possible for random web users to become lexicographers. But this time, the default will be Lexicographer-Basic, with privileges to edit entries but not to publish or delete. This way, over time, they can appeal to become Lexicographer-Pro when their work can be assessed.

When this is done, please notify me so I can make public the lexicographer guidelines which we currently only have to send via email to every new user we create.