Add read_psi ipython import

.ipython/profile_default/startup/50-imports.py

@@ -27,7 +27,9 @@ import m200_util
 import read_snapshot
 import read_snapshot.hdf5
 import read_snapshot.gadget
+import read_snapshot.read_psi
 import snapshot
+from read_snapshot.read_psi import read_psi
 from snapshot import Snapshot
 
 aconst = astropy.constants