remove ipython.py entry point

[minrk]

it's weird and confusing and not maintained well.

Adds a python -m IPython entry point in its place, which should work anywhere.

[rkern]

I believe IPython/__main__.py would be the preferred way to implement python -m IPython since Python 2.6.

[minrk]

Of course, that's already there, so I just removed my change. I don't know why I didn't check first. Thanks!

[tkf]

FYI, ipython.py and -m IPython are not equivalent as it seems IPython.main does not call update_submodules.

[minrk]

Nor should it, really. The point is that ipython.py is a little-used entry point that is not worth maintaining. Also python -m IPython notebook will do what it should regarding submodules / messages after #3275 is merged.

[fperez]

For the record, I'm +1 on this cleanup. Let's let it simmer for another day or two, to give others a chance to pitch in, and unless a valid objection arises, we can merge. Thanks!

[bfroehle]

Fine with me!

[bfroehle]

Also need to remove ipython.py from MANIFEST.IN, and fix examples/core/ipython_here_shell_extension.reg.

[minrk]

@bfroehle done, thanks

[ellisonbg]

Looks like this has been reviewed and everything looks good. Merging.