* lisp/eshell/esh-mode.el (eshell-clear): New function.
(eshell/clear): Fix incorrect behavior, and do the right thing when
'eshell-scroll-show-maximum-output' is nil.
(eshell/clear-scrollback): Call 'eshell/clear'.
* test/lisp/eshell/esh-mode-tests.el
(esh-mode-test/clear/eshell-command)
(esh-mode-test/clear/eshell-command/erase)
(esh-mode-test/clear/emacs-command)
(esh-mode-test/clear/emacs-command/erase): New tests.
* etc/NEWS: Mention the new 'eshell-command' (bug#73722).
* lisp/eshell/esh-mode.el (eshell-postoutput-scroll-to-bottom): Use
'get-buffer-window-list' for simplicity.
(eshell-handle-control-codes): Use 're-search-forward'; this way is much
faster.
* test/lisp/eshell/esh-mode-tests.el: New file.