[Twitter] protected/private metadata field

[Scripter17]

For some reason twitter just does not want to play nice with any accounts I make specifically for gallery-dl (it's 401 and even with supplied usernames and passwords it cuts me off after a while. Probably not fixable on gallery-dl's side), so I need to use my main

It would be handy if I could avoid accidentally sharing stuff from privated accounts I follow both to be nice and to reduce any risk of people finding my account, but there deosn't seem to be any metadata field I can put into extractor.*.image-filter for this

[mikf]

Each author/user now has a protected property. (108abab)