Merge from origin/emacs-26

758e9a8 Revert "Don't mark main_thread (Bug#36155)"
1877b7b Don't mark main_thread (Bug#36155)
4904fb3 More quotation fixes (Bug#35885)
4cc4b5d ; * src/keyboard.c (tool_bar_items): Fix a typo.  (Bug#36143)
b58ecaf Minor copyedits in efaq-w32
48422af Tiny improvement of documentation of major mode conventions
25d44d2 * nt/addpm.c (main): Fix buffer overflow

diff --cc doc/emacs/text.texi
Simple merge

diff --cc doc/lispref/modes.texi
Simple merge

diff --cc src/keyboard.c
Simple merge