Update4.1 handle num cpus (#669)

* Handle or avoid multiprocessing import errors during qutip.__init__()
factorial import in utilities moved into only function that uses it
multiprocessing import in __init__ within try

* multiprocessing import moved outside the try

qutip/__init__.py

@@ -140,7 +140,10 @@
     if 'cpus' in info:
         qutip.settings.num_cpus = info['cpus']
     else:
-        qutip.settings.num_cpus = multiprocessing.cpu_count()
+        try:
+            qutip.settings.num_cpus = multiprocessing.cpu_count()
+        except:
+            qutip.settings.num_cpus = 1
 
 
 # Find MKL library if it exists

qutip/utilities.py

@@ -40,8 +40,6 @@
            'view_methods']
 
 import numpy as np
-from scipy.misc import factorial
-
 
 def n_thermal(w, w_th):
     """
@@ -143,6 +141,8 @@ def clebsch(j1, j2, j3, m1, m2, m3):
         Requested Clebsch-Gordan coefficient.
 
     """
+    from scipy.misc import factorial
+
     if m3 != m1 + m2:
         return 0
     vmin = int(np.max([-j1 + j2 + m3, -j1 + m1, 0]))