* lisp/textmodes/string-edit.el (string-edit): Use pop-to-buffer
with fit-window-to-buffer after the buffer is filled with text.
(string-edit-done, string-edit-abort): Use (quit-window 'kill).
* lisp/textmodes/string-edit.el (string-edit)
(read-string-from-buffer): Rework the function arguments so that
they're more similar to `read-string'. Rename symbols throughout
the file from help-text to prompt.
* lisp/textmodes/string-edit.el (string-edit)
(read-string-from-buffer): Make doc strings use dynamic key
bindings.
(string-edit): Fix message at the end.
