[WIP] : QISKIT installer based on setuptools and Cython

[nonhermitian]

Provides a standard installation and build chain via setuptools.

Description

C++ code is compiled via Cython, and linked to the NumPy BLAS libraries automatically. Support for Windows, and Visual Studio 2015 (the only supported build chain on Windows) comes for free. The c++ simulators no longer need a PIPE call, and are now called like any other Python object.

Motivation and Context

Using make is not a standard way of building Python packages. Instead, this Pull implements the standard python setup.py install. Building the c++ extensions locally, for running unit tests, requires doing python setup.py build_ext --inplace, and the resulting binary is built in qiskit.cython. Wheels building is also a simple call: python setup.py bdist_wheel. Going forward, there is a clear path to integration with conda-forge.

This also helps to remedy issues such as #393, #340.

Benefits over current make process:

• Standard Python package build process; supports building on Windows, in the supported manner, seamlessly.
• Allows for linking c++ code to BLAS from NumPy; Intel MKL or openBLAS binding for free. Easy testing against multiple BLAS libraries.
• C++ extensions linked and called as standard Python modules.
• C++ exceptions raised to Python exceptions.
• C++ code can be unit tested via Python.
• Removes the hard-coding of conda in the install process.
• Easy pushing to Pypi and conda-forge.

How Has This Been Tested?

So far tested on OSX: Apple clang, HB clang, HB gcc

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• [] I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[nonhermitian]

Note that this will not pass until Travis is reconfigured for new install process.

[nonhermitian]

setup.py now has commands for test, lint, pep8, profile and coverage.

[nonhermitian]

Travis now works with the following build matrix:

Python 3.5:

• gxx-5

Python 3.6

• pyflakes, pep8
• gxx-5
• clang
• openBLAS
• OSX, xcode 9.2

The builds are tested against the latest Anaconda version of all the libraries. Currently pyflakes and pep8 fail since the source has some errors in it, e.g.

https://travis-ci.org/nonhermitian/arrogant_seahorse/jobs/369224424

[nonhermitian]

This has been moved to its own repo so that integration testing is easier to do:

https://github.com/nonhermitian/arrogant_seahorse

[atilag]

We are going to restore setup.py file, so anyone can use it directly without having to run cmake first. But cmake tool is still centric to our build system, so the setup.py file will rely on it.