Ref http://lists.gnu.org/archive/html/emacs-devel/2012-01/msg00543.html
* doc/lispref/variables.texi (Using Lexical Binding):
Mention that lexical-binding should be set in the first line.
* src/lread.c (syms_of_lread): Doc fix.
* lisp/emacs-lisp/tabulated-list.el, lisp/progmodes/f90.el:
Move lexical-binding file-local to line one.
* etc/NEWS: lexical-binding should be ine the first line.
* lisp/international/characters.el: Add L and R categories.
* lisp/subr.el (bidi-string-mark-left-to-right): Rename from
string-mark-left-to-right. Use category search.
* lisp/buff-menu.el (Buffer-menu-buffer+size): Callers changed.
Use this for Tabulated List mode.
* lisp/emacs-lisp/tabulated-list.el (tabulated-list-mode): Use a custom
glyphless-char-display table.
(tabulated-list-glyphless-char-display): New var.
* src/term.c (produce_glyphless_glyph): Handle cons cell entry in
glyphless-char-display.
* src/xdisp.c (lookup_glyphless_char_display)
(produce_glyphless_glyph): Handle cons cell entry in
glyphless-char-display.
(Vglyphless_char_display): Document it.