cmake: add test dependencies

Building the tests requires first building the header files.

Hide Pybind11Helper symbols when pybind11 hides its symbols.

Update readme, revert non-portable pybind11 2.1 suffix fix

Remove SWIG support, add compatibility with Eigen 3.3

Update travis doc directory for deploy.

Fix signed-unsigned comparison warnings in new pybind11 wrappers.

Remove NumPy C API usage from pybind11 wrappers

Merge pull request ndarray#61 from ndarray/pybind11

Fix regression in Eigen converter

Merge pull request ndarray#59 from ndarray/pybind11

Use NumPy 1.7 API for pybind11

Merge pull request ndarray#56 from ndarray/pybind11

Fix pybind11 type_casters to accept None as nullptr