closes#4142closes#4357closes#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.