new model mixins structure

models.mixins.list is now a reference file for future development

simplified get_views() function structure, removed need for viewsets

GET THOSE VIEWSETS OUUUUUUUUUUUUUUT
Allow action kwarg to AutoPatternsMixin.get_url to be a Django View (to get the action name using view.get_action_name())
* django_pstch_helpers/models/mixins/edit.py: new edition mixins