Eliminate 'vtable--limit-string' in favor of the more efficient
'truncate-string-pixelwise'. Remove extraneous pre-measurement
calls to 'string-pixel-width' and ellipsis concatenation as
'truncate-string-pixelwise' does both.
The 'make-vtable' 'ellipsis' keyword can be a string to override
the default returned by 'truncate-string-ellipsis'.
* lisp/emacs-lisp/vtable.el (vtable--ellipsis): New defun.
(vtable-insert-object, vtable--insert): Use 'vtable--ellipsis'.
(vtable--insert-line, vtable--insert-header-line): Call
'truncate-string-pixelwise' instead of 'vtable--limit-string'.
(vtable--limit-string): Remove function.
* test/lisp/emacs-lisp/vtable-tests.el
(test-vtable--limit-string-with-face-remapped-buffer): Remove
test, obsoleted by misc-test-truncate-string-pixelwise.
* doc/misc/vtable.texi: Document that :ellipsis can be a string.
48d65afa32