Show

Tweak ``show.prettyprint()`` to not automatically multi-line all
show output. If you want multi-line output, either set
``show.prettyprint(sep='\m')`` to globalize that preference, or
use ``show(..., sep='\n)`` each time you want multi-line.

Bug fix: When `show.set(prefix=...)` or other settings were used,
duplicate behaviors could occur, like two prefix strings printing,
not just one. Also, support for Python 2.6 has been restored. Not
that you should still be using that antiquated buggy. But if you
are, show will once again work for you, given removal of the
preventing dependency (``stuf``).

Fixed bug when location display is active (e.g. after
`show.set(where=True)`) in IPython. Now correctly identifies what
cell code was executed in.

Finally have good support for IPython, either in a Notebook or in
a terminal/console. Suddenly, interactive use does not minimize
show's usefulness (though the standard REPL still has glitches).

Fixes nasty packaging bug (failure to bundle astor sub-package
into source distributions) that didn't show up in testing.

Python 3.5 and 3.6 now pass formal verification. This required
embedding a 'nightly' build of astor 0.6 that has not yet made it
to PyPI. Given the shift from codegen to newer astor AST-to-source
library, bumping minor version.