Implementing PylmathShear.cpp using pybind11

[shreyas-koduvayur]

I did it in the pybind11 format

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: shreyas-koduvayur (6fb2094)

[cary-ilm]

Thanks for the contribution!

Because we are building up the pybind11 implementation incrementally, we have structured the repo so that the new implementation is under src/pybind11, in parallel with the long-standing implementation in src/python. Your implementation looks sound, except that it overwrites the src/python implementation, whereas we'd prefer it to go in a new file src/pybind11/PyBindImath/PybinBindImathShear.cpp. Note also that you'll need to add this to src/pybind11/CMakeFile.txt, and you also need to invoke register_imath_shear from the module definition in src/pybind11/PyBindImath/pybindimathmodule.cpp