Improve display of tex-verbatim and Info quoted

Improve display of tex-verbatim and Info quoted

Problem reported by Glenn Morris (Bug#19889).
* doc/emacs/display.texi (Standard Faces):
* doc/lispref/display.texi (Basic Faces):
* etc/NEWS: Mention fixed-pitch-serif.
* lisp/faces.el (face-font-family-alternatives):
New family alias Monospace Serif.
(fixed-pitch-serif): New face, which uses the new family.
* lisp/info.el (Info-quoted):
* lisp/textmodes/tex-mode.el (tex-verbatim): Use the new face.
* test/lisp/legacy/font-parse-tests.el (font-parse-tests--data):
Add test case for Monospace Serif.