make PyPI package with build script that includes NUPACK and ViennaRNA

[dave-doty]

numpy can be installed from pip, despite having lots of compiled C and Fortran code.

Presumably there should be some way to make for dsd a PyPI package installable from pip, which would include NUPACK and ViennaRNA. Pre-compiled binaries would be ideal to avoid installation headaches for users. Not sure how numpy does it (pre-compiled binaries, or compilation during setup).

But, if pre-compiled binaries are not an option, then it should be straightforward to make a Python package that simply installs with the dependencies currently listed in requirements.txt (which does not include NUPACK or ViennaRNA). The hard part will be NUPACK, which is not open-source and requires a user to register with the nupack website before downloading the package, so there's no way to simply declare NUPACK's Python package as a dependency in setup.py and have pip automatically install it.

[dave-doty]

See #139 for a simpler issue about creating a PyPI package that does not include the NUPACK and ViennaRNA binaries.