Remove the ability to authenticate to the API with the `login` and
`password_hash` url parameters. This is a legacy authentication method
from Danbooru 1. How to actually generate the password_hash for this
method hasn't been fully documented for many years now. It required
taking the SHA1 hash of your password combined with an undocumented salt
value (i.e., password_hash = sha1("choujin-steiner--#{password}")).
This authentication method was also slow because it required checking
the password on every API call. Checking passwords is deliberately slow
because passwords are hashed with BCrypt. BCrypt takes about ~200ms per
request, so using this method effectively limited you to ~5 requests per
second in a single thread.
e9b33dbd48