[Cython] cython namespace

[Stefan Behnel]

Hi,

Dag Sverre Seljebotn wrote:
> I'm still for "flat better than nested", but failing that, I'd propose
> that everything is in cython.buffer but shape is also in cython.

Could we wait with the latter until we actually have something different than
buffers that it's worth getting the shape of? Until then, I think everything
that relates to buffers should be in cython.buffer. People can do their
cimports as they like anyway, but it should be clear where things are coming from.

Stefan