Update login forms and lib users/Auth

* One form for login and admin/login used
* Re-confirm login on admin/login if user logged in, otherwise presents default login-form
Update config routes for login forms
Update core/Admin_Controller to check for logged_in_admin
Merge branch 'feature/users' into develop
Fix typo in config/autoload.sample
Update core/ICF_Model to check for empty prepped data
Layout fix of lang english/icf_button
Update module users to allow sending new confirmation code
Merge branch 'feature/users' into develop
Update core/ICF_Model: Officially deprecate $this->formitem
Update models of module settings to use numeric primary keys
Update core/Nested_set_Model to work with id == '1' for item "ROOT"
Update module 'acl' models to use integer primary keys
Update lib acl/Acl to use primary-key == '1' for "ROOT"
Update ctlrs of module 'acl' to work with integer primary-keys
Update model users/user to work with integer primary key (length 16)
Update file-template "model": Remove deprecated "$input"
Update migrations to:

* Integer primary keys
* Use dbforge instead of pure MySQL-queries
Update helper ICF_array

* Add function dp()
* Uses ob_buffer for dd() and dp()
Merge branch 'feature/app-cores' into develop