Feature/allow model meta fields inheritance and more

[ADR-007]

[Merge after ADR-007:bugfix/fix-model-list-subcollections]

• Allow model._meta field inheritance
• Allow change default manager class
• Use id as default doc_id field (it is before, but implicit and not always)
• Add by_colum_name to Model.from_dict
• Fix ordering by nested fields
• Add Meta.column_name_generator (can be used to generate camelCase column names)
• Add Model.refresh
• Add model.merge_with_dict
• Add IDField.include_in_document
• Set Meta.abstract = True in base model
• Save doc.id on batch create
• Add Meta.collection_name_generator
• Use collection.parent() in .create()
• Generate Model.id by IDField
• Allow required=True in IDField
• Add default_factory
• Add copy for default values