* lisp/simple.el (goto-line): Don't display default line number in the

* lisp/simple.el (goto-line): Don't display default line number in the
prompt because it should be displayed by `read-number' (bug#9952).
Add the current line number to the defaults of `goto-line' to
allow its easier modification by users with `M-n' (bug#9201).

* lisp/subr.el (read-number): Support multiple default values like in
other minibuffer reading functions.  Replace `read' with
`string-to-number' for consistency with `number-to-string'.