Log Message:
py-sympy: update to 1.1.1

Changes 1.1.1:

Units
-----
Fix an issue with the Quantity Add postprocessor in Python 3.6.
Support functions with quantities and dimensions.
Fix addition of a quantity and a number.
Workaround power of a quantity.
Fix SI prefix definitions

Core
----
Fix the Add/Mul postprocessor logic for subclasses.
Fix various recursion issues in the Add assumptions that prevented isympy from \ 
working with the cache off.
Fix some test failures on 32-bit systems.
Allow for complex NumPy scalars in sympify.

Code generation
---------------
Only call asarray in lambdify on Python builtin numeric types. Fixes lambdify \ 
for array subclasses such as xarray.
Fix using preprocessor_statements kwarg in CCodeGen.

Matrices
--------
Fix stacking of empty matrices.

Other
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Build the docs with the latest version of Sphinx. Fixes the search functionality \ 
being broken in the docs.
Fix the language classifiers in setup.py