Quoting fixes in lisp/textmodes

Quoting fixes in lisp/textmodes

* lisp/textmodes/bibtex.el (bibtex-validate)
(bibtex-validate-globally, bibtex-search-entries):
* lisp/textmodes/ispell.el (ispell-command-loop):
* lisp/textmodes/page-ext.el (search-pages, pages-directory):
* lisp/textmodes/texinfmt.el (texinfmt-version)
(texinfo-format-region, texinfo-format-buffer-1):
* lisp/textmodes/two-column.el (2C-split):
Respect text quoting style in doc strings and diagnostics.
* lisp/textmodes/conf-mode.el (conf-mode-map, conf-quote-normal):
* lisp/textmodes/sgml-mode.el (sgml-specials, sgml-mode):
Escape apostrophes in doc strings.