Normalize mpf in mp.npconvert() and lower precision in tests

On most systems np.float128 aren't IEEE 754 quadruples.

Closes #836

mpmath/ctx_mp_python.py

@@ -704,7 +704,7 @@ class PythonMPContext:
         import numpy as np
         if isinstance(x, np.ndarray) and x.ndim == 0: x = x.item()
         if isinstance(x, (np.integer, int)): return ctx.make_mpf(from_int(int(x)))
-        if isinstance(x, (np.floating, float)): return ctx.make_mpf(from_npfloat(x))
+        if isinstance(x, (np.floating, float)): return ctx.mpf(from_npfloat(x))
         if isinstance(x, (np.complexfloating, complex)):
             return ctx.make_mpc((from_npfloat(x.real), from_npfloat(x.imag)))
         raise TypeError("cannot create mpf from " + repr(x))

mpmath/tests/test_convert.py

@@ -263,9 +263,9 @@ def test_compatibility():
     assert mpf(np.float64('inf')) == inf
     assert isnan(mp.npconvert(np.float64('nan')))
     if hasattr(np, "float128"):
-        mp.prec = 113
+        mp.prec = 64
         assert (mp.npconvert(np.float128('0.841470984807896506652502321630298954')) ==
-                mpf('0.841470984807896506664590813295845351'))
+                mpf('0.841470984807896506653'))
     mp.prec = 53
     # issues 382 and 539
     assert mp.sqrt(np.int64(1)) == mpf('1.0')