Wrap as much code as needed to make testWarper.py and testWarpExposure.py work and enable that test.
Complete afw port to pybind11
Wrap afw::cameraGeom with pybind11
I had to wrap warping code, MaskedImage varieties of SinglePixel, and DecoratedImage
I don't understand why SinglePixel had to be wrapped. It doesn't appear to be in the python API in the current (SWIG) stack and a quick grep didn't reveal SinglePixel used in any *.i or *.py files.
This was needed to provide the usual default value for the padValue argument of the warping functions templated on MaskedImage. I don't know how the SWIG handled that argument; it didn't occur to me to check if it was supported. It may prove useful, though I don't think it is currently specified by any python code.
Everything looks good, just a few minor corrections.