plugins: Keep compatibility with old plugins location

dream/plugins/__init__.py

@@ -22,3 +22,8 @@ try:
 except ImportError:
     from pkgutil import extend_path
     __path__ = extend_path(__path__, __name__)
+
+# BBB Add compatibility names for plugins that moved.
+from DemandPlanning import AddDemandPlannerGenerator
+from DemandPlanning import DemandPlanningLine
+from DemandPlanning import PostProcessDemandPlanning