Refactor %magic into a lsmagic_docs API function.

[bfroehle]

From @fperez in #1999:

@bfroehle, I think %magic -brief was added for doc generation at some point, which is obviously a bit of a hack, though I'm not totally sure anymore.

The right answer now would obviously be to move that functionality into the magics manager as an api call, and let the magic call be strictly for human-friendly use with direct printing.

I've added a lsmagic_docs method which returns a dictionary of magic function docstrings. It optionally takes parameters brief (list only first line of the docstring) and missing (to use in lieu of an empty docstring).

[bfroehle]

Test results for commit fa1cdf9 merged into master
Platform: linux2

• python2.7: OK
• python3.2: OK (libraries not available: oct2py pymongo rpy2 wx wx.aui)

Not available for testing: python2.6, python3.1

[fperez]

Do you want to change %magic -brief now to actually do the printing so it's more human-friendly?

[bfroehle]

Aha, yes. Thanks!

[bfroehle]

If the button doesn't seem to work, I guess pushing it a bunch of times isn't the solution. Sorry for the spam.

[fperez]

No worries, it's happened to me too :)

[fperez]

Thanks, merging now then!