Merge branch 'feature/tabs'

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

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

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

diff --cc etc/NEWS
Simple merge

diff --cc etc/TODO
Simple merge

diff --cc lisp/frame.el
Simple merge

diff --cc lisp/menu-bar.el
Simple merge

diff --cc lisp/mouse.el
Simple merge

diff --cc lisp/startup.el
Simple merge

diff --cc lisp/subr.el
Simple merge

diff --cc lisp/window.el
Simple merge

diff --cc lisp/xt-mouse.el
Simple merge

diff --cc src/buffer.c
Simple merge

diff --cc src/buffer.h
Simple merge

diff --cc src/keyboard.c
Simple merge

diff --cc src/lisp.h
Simple merge

diff --cc src/term.c
Simple merge

diff --cc src/w32fns.c
Simple merge

diff --cc src/window.c
Simple merge

diff --cc src/xdisp.c
Simple merge

diff --cc src/xfaces.c
Simple merge

diff --cc src/xterm.c
Simple merge