switch to python entry_points

[carlodri]

It seems like entry_points in setup.py should be preferred over scripts whenever possible (see here). This improves cross-platform compatibility and is also works better with conda-forge (where I just uploaded a recipe for this package).

By the way, @svanoort if you wish to be added as package maintainer con the conda-forge feedstock, just drop me a line or make a PR there adding yourself.