Co-authored-by: Henry Schreiner <HenrySchreinerIII@gmail.com>

Moving tp_class access, and consistent fully-qualified naming for PyPy, to detail::get_tp_name (#2520)

* Moving tp_class access, and consistent fully-qualified naming for PyPy, to detail::get_tp_name

* Change get_tp_name to get_fully_qualified_tp_name

On very incomplete python installations (e.g. within Docker), it's
possible that distutils is not installed. In that case, the
``execute_command`` statement that queries distutils for the Python
module extension fails, and pybind11 uses the empty string. This commit
adds an extra check that causes a CMake failure with more actionable
information (just spent a lot of time trying to track down this problem :))

* ci: releases

* docs: minor update form @wjakob

* fix: enforce reasonable version of setuptools

* Initializing PyModuleDef object with PyModuleDef_HEAD_INIT.

Python 3.8 documentation: m_base - Always initialize this member to PyModuleDef_HEAD_INIT.

Long-standing (since first github commit in 2015), inconsequential bug.

Also removing inconsequential Py_INCREF(def): PyModule_Create() resets the reference count to 1.

* git rebase master

* moving static PyModuleDef declaration to global scope, as requested by @wjakob

* renaming the two new macros, to start with PYBIND11_DETAIL_MODULE

Fixed in #2510 but reintroduced on one line by #2126

Closes #2515, found by @rhjdjong

This changes enum reprs to look like `<Enum.name: value>` similarly to
the Python enum module.

This keeps the str of enums as `Enum.name`, like the Python enum module.

* Include what is used

* Separated the C++ standard library headers and the project headers

* Reordering includes

* fix: AppleClang 12 new warning

* Fix: AppleClang X.X.0 will not trigger this warning

* ci: fix broken documenation test (works on RtD)

* docs: docs link incorrect

* docs: read version from pybind11 file

* docs: show full PEP 440 version everywhere

This now tests the old form too, and fixes the bug introduced.

* docs: installing section

* docs: feedback from @wjakob

Support C++20. For backwards compatibility, we provide an alias for the old name.
This change is necessary to easily avoid errors when a compiler thinks
`module` is used as a keyword.

* refactor: drop mkdoc

* docs: update changelog

* feat: setup.py redesign and helpers

* refactor: simpler design with two outputs

* refactor: helper file update and Windows support

* fix: review points from @YannickJadoul

* refactor: fixes to naming and more docs

* feat: more customization points

* feat: add entry point pybind11-config

* refactor: Try Extension-focused method

* refactor: rename alt/inplace to global

* fix: allow usage with git modules, better docs

* feat: global as an extra (@YannickJadoul's suggestion)

* feat: single version location

* fix: remove the requirement that setuptools must be imported first

* fix: some review points from @wjacob

* fix: use .in, add procedure to docs

* refactor: avoid monkeypatch copy

* docs: minor typos corrected

* fix: minor points from @YannickJadoul

* fix: typo on Windows C++ mode

* fix: MSVC 15 update 3+ have c++14 flag

See <https://docs.microsoft.com/en-us/cpp/build/reference/std-specify-language-standard-version?view=vs-2019>

* docs: discuss making SDists by hand

* ci: use pep517.build instead of manual setup.py

* refactor: more comments from @YannickJadoul

* docs: updates from @ktbarrett

* fix: change to newly recommended tool instead of pep517.build

This was intended as a proof of concept; build seems to be the correct replacement.

See https://github.com/pypa/pep517/pull/83

* docs: updates from @wjakob

* refactor: dual version locations

* docs: typo spotted by @wjakob

* refactor: replace .get_type with type::handle_of

* refactor: use impl for handle_of

* fix: deprecate h.get_type()

* Add vcpkg installation instructions

* Casing

* Move instructions

Co-authored-by: Henry Fredrick Schreiner <henry.fredrick.schreiner@cern.ch>

* fix: use OVERRIDE instead of OVERLOAD

* docs: more accurate statement

Change base parameter type in register_exception and exception constructor from PyObject* to handle (#2467)

* Change base parameter type in register_exception and excepion constructor from PyObject* to handle

* Fix compilation error passing `handle` to `PyObject*`

```
/pybind11/include/pybind11/iostream.h:71:9: warning: Call to virtual method 'pythonbuf::sync' during destruction bypasses virtual dispatch [clang-analyzer-optin.cplusplus.VirtualCall]
        sync();
        ^
/pybind11/tests/test_iostream.cpp:72:5: note: Calling '~scoped_ostream_redirect'
    });
```