master updated (17eae91 -> b56401f)

[Glenn Morris]

gm pushed a change to branch master.

      from  17eae91   Use lexical-binding in most eshell tests
      adds  ac31cd3   * etc/NEWS: Fix inconsistencies.
      adds  68f4a74   Remove doc duplication
      adds  f0b9f18   Make shell-command tests fit for tcsh.
      adds  f0e1bf5   Fix bugs in tab-bar and tab-line and mention remaining 
features in manual.
      adds  1f76a16   * lisp/image-mode.el (image-mode-map): Update menu items.
      adds  9f5ae71   * test/lisp/simple-tests.el 
(with-shell-command-dont-erase-buffer):
      adds  0278741   Fix typo in custom.texi
      adds  16fed05   Avoid crashes on TTY frames with over-long compositions
      adds  d83cc05   Fix error in ERC when 'erc-server-coding-system' is 
customized
      adds  85544f8   * lisp/isearch.el: Fix lazy-highlighting and 
lazy-counting of hidden matches
      adds  520fd3e   * lisp/env.el (substitute-env-vars): Doc fix.  (Bug#40948)
      adds  2f9bfae   ; Fix last change
       new  b56401f   Merge from origin/emacs-27


Summary of changes:
 doc/emacs/custom.texi     |  2 +-
 doc/emacs/frames.texi     | 57 ++++++++++++++++++++++++++++++++++++++++++++---
 doc/emacs/windows.texi    | 12 ++++++++--
 doc/lispref/objects.texi  |  3 +--
 etc/NEWS.27               | 16 ++++++-------
 lisp/env.el               |  8 +++----
 lisp/erc/erc-backend.el   |  3 ++-
 lisp/image-mode.el        | 20 +++++++++++------
 lisp/isearch.el           |  7 ++++--
 lisp/tab-bar.el           | 38 ++++++++++++++++++++-----------
 lisp/tab-line.el          |  6 ++++-
 src/term.c                |  2 +-
 test/lisp/simple-tests.el | 11 ++++-----
 13 files changed, 135 insertions(+), 50 deletions(-)