add locate entry points

[minrk]

These would be useful for quickly locating IPython directories and profiles from other (non-Python) applications.

Examples:

$> ipython locate
/Users/me/.ipython

$> ipython locate profile foo
/Users/me/.ipython/profile_foo

$> ipython locate profile 
/Users/me/.ipython/profile_default

$> ipython locate profile dne
[ProfileLocate] Profile u'dne' not found.

locate profile is also available as profile locate, since that subcommand tree already exists.

[takluyver]

Do we also have documentation on how to find them from Python code, i.e. starting from IPython.config import ...?

[minrk]

For ipython_dir, absolutely, but I don't think there is a prominent mention for utils.path.locate_profile(name).

[minrk]

I added a simple doc section describing these entry points, and the corresponding utility functions.

[takluyver]

Is it deliberate to allow both ipython profile locate foo and ipython locate profile foo? It seems kind of unpythonic to offer two similar commands for the same thing.

[minrk]

It's in both because I didn't know which one to choose. If there were no other commands, locate profile foo makes more sense because it's an actual sentence. But we already have an ipython profile subtree of commands, so it seemed weird for it to not be there. I will add ipython locate profile foo to the ipython profile help, if you think that's best, and remove the ipython profile locate entry point.

[takluyver]

OK - I'm fairly neutral on which is better, but I think I marginally prefer having the locate commands together, so I'd remove ipython profile locate. Adding a note in the help makes sense too.

[minrk]

ipython profile locate removed

[takluyver]

Thanks, I think the doc section looks good.

[fperez]

This looks very useful, and after the review and fixes I see no reason to delay it further. Thanks guys! Going in...