bug#32939: 27.0.50; Don't reject confusable quotes, just fontify & mention them in error messages

[Noam Postavsky]

Severity: wishlist

As a followup from [1], here is a patchset which replaces the master's
current rejection of confusable quotes on `read', and instead adds a
hint to the error message when evaluating an expression with a
confusable quote leads to an error.

And also highlight such quotes with warning-face.

[1]: https://lists.gnu.org/archive/html/emacs-devel/2018-02/msg00093.html

v1-0001-Stop-signaling-an-error-when-reading-smart-quotes.patch
Description: patch

v1-0002-Give-suggestions-on-errors-about-var-names-with-c.patch
Description: patch