Merge from origin/emacs-26

Merge from origin/emacs-26

83187cd (origin/emacs-26) Skip mouse-face overlap check when mouse-fa...
a6d8f2b Fix capitalization of "Mail-Followup-To"
f9640f9 * lisp/progmodes/grep.el (grep-compute-defaults):
3a26c8a Semantic manual fixes
106a9f6 More improvements in the Emacs manual
244db85 * doc/misc/viper.texi (File and Buffer Handling): Add missing...
f0d6a16 Fix documentation of 'x-underline-at-descent-line'
69a8f45 * lisp/textmodes/flyspell.el (flyspell-get-word): Doc fix.
05214c6 Correct variable markup in manuals
355c644 Improve the "Sending Mail" chapter of Emacs manual

Conflicts:
	src/nsterm.m
	src/w32term.c