Overriding field names when binding structured dtypes

[aldanor]

This is a very small but useful addition -- PYBIND11_NUMPY_DTYPE_EX() can be used to provide custom names to exported fields. Since it's quite common in C++ to have suffices/prefices (e.g. underscores) for private members, this allows to easily overcome this ugliness when exporting types to numpy.

The example can be seen in the added test.

[wjakob]

Ok -- looks good to me. Please don't forget to add documentation for this and the other NumPy changes :)

[aldanor]

Yep, also will need to scan the several latest months for changes and add them to change log, lots of stuff is missing from there. Maybe we'll need to break release notes for 2.x in subsections, too.

[aldanor]

On a side note, I've definitely gained a few levels in higher-kinded C macros ))

[wjakob]

heh, yes -- and in writing portable ones ;). Regarding changelog: it's indeed starting to look that way. Not a bad thing though, v2.0 will be an exciting release.