include setup.py

[slayoo]

(https://sourceforge.net/p/gnudatalanguage/feature-requests/11/)

As requested back in 2005 by @smaret, it would be useful for Python users for GDL to ship with a setup.py script that would place the Python module in the correct location (probably this could also be triggered by make install).

[slayoo]

http://github.com/pybind/pybind11 includes the machinery needed to compile CMake-based C++ programs from within setup.py, and also to easily ship it through PyPi and conda-forge

[slayoo]

... and then mybinder.org provides the necessary functionality to execute a Jupyer notebook interactively for a given .ipynb file hosted at github.

To summarise, if we would be able to:

• revive the idl_kernel support for GDL (https://github.com/gnudatalanguage/idl_kernel)
• make a working setup.py script based on pybind11 that enables one to do "pip install gdl" (for the python module)
• upload the gdl module to PyPI
• prepare examples as .ipynb notebook files (written in GDL)

we would then get the ability to offer interactive demos of any functionality of GDL to anonymous users with just a single click (and no other needed infrastructure on our or users side)!