[forms] Add autocomplete attribute for formrenderers If you set form.autocomplete = False, the form renderer in the open form tag will add the html option 'autocomplete=off'. It allows to disable the functionality of some browsers to fill in some forms automatically (for instance a profile with login/password) Closes #3747294

option_group_changed('port', 'main', 'web')
option_group_changed('query-log-file', 'main', 'web')
option_group_changed('profile', 'main', 'web')
option_group_changed('max-post-length', 'main', 'web')