Remove the token.h header file. There was never any public tokenizer
C API. The token.h header file was only designed to be used by Python
internals.
Move Include/token.h to Include/internal/pycore_token.h. Including
this header file now requires that the Py_BUILD_CORE macro is
defined. It no longer checks for the Py_LIMITED_API macro.
Rename functions:
* PyToken_OneChar() => _PyToken_OneChar()
* PyToken_TwoChars() => _PyToken_TwoChars()
* PyToken_ThreeChars() => _PyToken_ThreeChars()
Only sequence of ASCII digits is now accepted as a numerical reference.
The group name in bytes patterns and replacement strings can now only
contain ASCII letters and digits and underscore.
Victor Stinner
Serhiy Storchaka
Ezio Melotti