fixes

ptycho/__init__.py

@@ -1,3 +1,8 @@
 from .base import PtychoEngine
 from .ptycho_example import ExamplePtychoEngine
-from .fold_slice import FoldSlicePtychoEngine
+from .fold_slice import FoldSlicePtychoEngine
+
+engines = {
+    'fake':       ExamplePtychoEngine,
+    'fold_slice': FoldSlicePtychoEngine
+}