MAINT: Re-export CustomFactor in zipline.pipeline.

tests/pipeline/test_engine.py

@@ -39,7 +39,7 @@ from zipline.pipeline.loaders.equity_pricing_loader import (
     USEquityPricingLoader,
 )
 from zipline.pipeline.engine import SimplePipelineEngine
-from zipline.pipeline.factor import CustomFactor
+from zipline.pipeline import CustomFactor
 from zipline.pipeline.factor.technical import (
     MaxDrawdown,
     SimpleMovingAverage,

zipline/pipeline/__init__.py

@@ -1,5 +1,5 @@
 from .classifier import Classifier
-from .factor import Factor
+from .factor import Factor, CustomFactor
 from .filter import Filter
 from .term import Term
 from .graph import TermGraph