OMG a ridiculous commit to overhaul import handler config etc.

- register all import/export handlers via setup.py and config
- use "handler key" lookup for all import/export commands
- fix logic bugs w/ CORE -> Trainwreck importer

rattail_corepos/corepos/office/commands.py

@@ -60,18 +60,9 @@ class ExportLaneOp(commands.ImportSubcommand):
     """
     name = 'export-lane-op'
     description = __doc__.strip()
-    default_handler_spec = 'rattail_corepos.corepos.lane.importing.op.office:FromCoreOfficeToCoreLane'
+    handler_key = 'to_corepos_db_lane_op.from_corepos_db_office_op.export'
     default_dbkey = 'default'
 
-    def get_handler_factory(self, **kwargs):
-        if self.config:
-            spec = self.config.get('corepos.lane.importing', 'office.handler',
-                                   default=self.default_handler_spec)
-        else:
-            # just use default, for sake of cmd line help
-            spec = self.default_handler_spec
-        return load_object(spec)
-
     def add_parser_args(self, parser):
         super(ExportLaneOp, self).add_parser_args(parser)
         parser.add_argument('--dbkey', metavar='KEY', default=self.default_dbkey,