Init big php login refactoring.
Fix consts using points. Clean up.
[Not tested] Perform huge giant refactoring
[Not tested] Perform huge giant refactoring. Remove SESSION, messages[] usage. Make parameters more explicit. Fix potential bugs.
[Not tested] Make get_cookie_part function internal parameters more explicit
Refactor mail DI. Remove user_name.
Make sign up endpoint working!
Make working sign up, in, out.
Fix readme typo
Fix classical trailed password problem: add string trimmers everywhere. Clean up.
profile: Add ctrl+enter processor. Clean up.
Make working reset password feature.

Add interface wrapper over model.
Prevent  user existing information propagation.
Make get_user_by_id() more functional (add property specify possibility for DB performance reasons).
Rename Model::store_password_reset_data() for more informative.
Clean up.
Add server tokens interface.
Move database calls into Model.
Merge branch 'big-php-login-refactoring' into develop