* Add missing header files to pythoncore.
* Add missing file filters ("Resource Files" in particular) to
all projects.
* Add new sub-filters for private headers in pythoncore and
for 3rd party source files.
* Add missing _zoneinfo configurations in pcbuild.sln.
* Update bdist_wininst with the new zlib location.
Add a new _testinternalcapi module to test the internal C API.
Move _Py_GetConfigsAsDict() function to the internal C API:
_testembed now uses _testinternalcapi to access the function.