Please consider installing Python-versioned 'ipythonX.Y' executable

Currently, ipython seems to install just `ipython` and `ipython3`. However, many users are using IPython like Python, and request having `ipython2.7`, `ipython3.2` etc. to be able to easily experiment with particular version of choice.

Debian already did it for some time [[1](https://packages.debian.org/jessie/all/ipython/filelist)], and this has been lately requested in Gentoo [[2](https://bugs.gentoo.org/show_bug.cgi?id=496010)]. Could you consider installing such a versioned executable directly via `setup.py`?