* Always capitalize Eigen

* Fix spelling

I think this particular method binding should not be done with `PYBIND11_OVERLOAD_PURE` but instead `PYBIND11_OVERLOAD`.

Bazel has a "strict" build model that requires all C++ header files be compilable on their own, and thus must explicitly #include all headers they require (even if de facto header inclusion order means they'd get them "for free"). This adds a couple of headers that are needed (but missing) by this model.

* doc: Add note about casting from `None` to `T*`

* doc: reword 'none-to-pointer' note message

* doc: mention opaque types in 'none-to-pointer' note message

* Added __contains__ to stl bindings for maps

* Added note regarding make install

* Fixing order of arguments in call to PyErr_GivenExceptionMatches in pybind11::error_already_set.matches

* Added tests on error_already_set::matches fix for exception base classes

Since the module is named FindPythonLibsNew, PythonLibsNew_FOUND should be set appropriately.

* Fix warning that not including a cmake source or build dir will be a fatal error (it is now on newest CMakes)
    * Fixes appveyor
* Travis uses CMake 3.9 for more than a year now
* Travis dropped sudo: false in December
* Dropping Sphinx 2
- clang7: Suppress self-assign warnings; fix missing virtual dtors
- pypy:
  - Keep old version (newer stuff breaks)
  - Pin packages to extra index for speed
- travis:
  - Make docker explicit; remove docker if not needed
  - Make commands more verbose (for debugging / repro)
  - Make Ubuntu dist explicit per job
- Fix Windows
- Add names to travis

Cf. https://docs.pytest.org/en/latest/deprecations.html#pytest-namespace

This avoids GIL deadlocking when pybind11 tries to acquire the GIL in a thread that already acquired it using standard Python API (e.g. when running from a Python thread).

[ci skip]

* Adds std::deque to the types supported by list_caster in stl.h.
* Adds a new test_deque test in test_stl.{py,cpp}.
* Updates the documentation to include std::deque as a default
  supported type.

* Add possible solution to ImportError issue

* Check default holder

-Recognize "std::unique_ptr<T, D>" as a default holder even if "D" doesn't match between base and derived holders

* Add test for unique_ptr<T, D> change

Pybind11 provides a cast operator between opaque void* pointers on the
C++ side and capsules on the Python side. The py::cast<void *>
expression was not aware of this possibility and incorrectly triggered a
compile-time assertion ("Unable to cast type to reference: value is
local to type caster") that is now fixed.

* Support C++17 aligned new statement

This patch makes pybind11 aware of nonstandard alignment requirements in
bound types and passes on this information to C++17 aligned 'new'
operator. Pre-C++17, the behavior is unchanged.

This PR brings the std::array<> caster in sync with the other STL type
casters: to accept an arbitrary sequence as input (rather than a list,
which is too restrictive).

Add a detailed link to Python 3 documentation.  Add a caveat about
the program terminating if initializing the interpreter fails.

* Issue #1532: Incompatible config options, /MP vs /Gm for MSVC in DEBUG