Move SphinxSmartQuotes transform to SphinxStandaloneReader

closes #4142
closes #4357
closes #4359
refs: #3967

Adds ``smartquotes``, ``smartquotes_action``, ``smartquotes_excludes``
configuration variables.

- if ``smartquotes`` is set to False, then Smart Quotes transform is not
  applied even if a Docutils configuration file activates it,

- the current default of ``smartquotes_excludes`` deactivates Smart
  Quotes for Japanese language, and also for the ``man`` and ``text``
  builders.

  However, currently ``make text html`` deactivates Smart Quotes for
  ``html`` too, and ``make html text`` activates them for ``text`` too,
  because the picked environment is shared and already transformed.

- now Smart Quotes get applied also when source documents are in
  Markdown or other formats.

1 files changed, 3 insertions, 4 deletions

diff --git a/sphinx/parsers.py b/sphinx/parsers.py
index b58eefa23..1aa16a45e 100644
--- a/sphinx/parsers.py
+++ b/sphinx/parsers.py
@@ -13,8 +13,6 @@ import docutils.parsers
 import docutils.parsers.rst
 from docutils.transforms.universal import SmartQuotes
 
-from sphinx.transforms import SphinxSmartQuotes
-
 if False:
     # For type annotation
     from typing import Any, Dict, List, Type  # NOQA
@@ -60,10 +58,11 @@ class RSTParser(docutils.parsers.rst.Parser):
 
     def get_transforms(self):
         # type: () -> List[Type[Transform]]
-        """Sphinx's reST parser replaces a transform class for smart-quotes by own's"""
+        """Sphinx's reST parser replaces a transform class for smart-quotes by own's
+
+        refs: sphinx.io.SphinxStandaloneReader"""
         transforms = docutils.parsers.rst.Parser.get_transforms(self)
         transforms.remove(SmartQuotes)
-        transforms.append(SphinxSmartQuotes)
         return transforms