Replace ASCII-quotes with proper markup.

doc/src/sgml/arch-pg.sgml

doc/src/sgml/catalogs.sgml

doc/src/sgml/charset.sgml

doc/src/sgml/cvs.sgml

doc/src/sgml/datatype.sgml

doc/src/sgml/datetime.sgml

doc/src/sgml/docguide.sgml

doc/src/sgml/ecpg.sgml

doc/src/sgml/extend.sgml

doc/src/sgml/geqo.sgml

doc/src/sgml/history.sgml

doc/src/sgml/indexcost.sgml

doc/src/sgml/inherit.sgml

doc/src/sgml/jdbc.sgml

doc/src/sgml/libpgtcl.sgml

doc/src/sgml/libpq++.sgml

doc/src/sgml/libpq.sgml

doc/src/sgml/lobj.sgml

doc/src/sgml/manage-ag.sgml

doc/src/sgml/manage.sgml