fix: add basic execution methods for batch handler

also logic for batch data files, and deletion

docs/glossary.rst

@@ -112,6 +112,12 @@ Glossary
      "inventory batch" would use another.  And each "type" would be
      managed by its own :term:`batch handler`.
 
+     The batch type is set on the model class but is also available on
+     the handler:
+
+     * :attr:`wuttjamaican.db.model.batch.BatchMixin.batch_type`
+     * :attr:`wuttjamaican.batch.BatchHandler.batch_type`
+
    command
      A top-level command line interface for the app.  Note that
      top-level commands don't usually "do" anything per se, and are