Rename xadapt() -> adapt()

[stuarteberg]

Fixes #546

Technically, this is a breaking change, albeit a small one. Does that mean it should wait until the next major release?

cc @constantinpape

details

# Rename xadapt -> adapt
$ git grep -l xadapt | xargs sed -i '' 's/xadapt\([^a-zA-Z.]\)/adapt\1/g'

# Note: Header name is unchanged.
$ git grep xadapt
CMakeLists.txt:    ${XTENSOR_INCLUDE_DIR}/xtensor/xadapt.hpp
docs/source/adaptor.rst:    #include "xtensor/xadapt.hpp"
docs/source/adaptor.rst:    #include "xtensor/xadapt.hpp"
docs/source/adaptor.rst:    #include "xtensor/xadapt.hpp"
docs/source/api/xarray_adaptor.rst:Defined in ``xtensor/xadapt.hpp``
docs/source/api/xtensor_adaptor.rst:Defined in ``xtensor/xadapt.hpp``
docs/source/external-structures.rst:``xadaptor_semantic`` instead.
include/xtensor/xnpy.hpp:#include "xtensor/xadapt.hpp"
test/CMakeLists.txt:    test_xadapt.cpp
test/CMakeLists.txt:    test_xadaptor_semantic.cpp
test/test_xadapt.cpp:#include "xtensor/xadapt.hpp"

[JohanMabille]

Hi Stuart,

Thanks for fixing this! It is not a problem to merge it now since we plan to add other breaking changes and make a major release shortly (I should say minor actually, since that will be 0.14.0).