bug#9917: bug#5042: bug#9917: 24.0.90; Make `goto-line' consistent with the line number from the minibuffer

[Juri Linkov <juri@linkov.net>]

>> 2. Re-bind 'M-g g' to goto-line-relative as many asked to do
>>    with the reasoning that 'M-g g' should use by default the
>>    same numbering scheme as is displayed by display-line-numbers-mode;
>
> Two comments:
>
>  1) display-line-numbers-mode by default behaves the same as
>     line-number-mode
>  2) display-line-numbers-mode has the display-line-numbers-widen
>     option which disregards narrowing, so if you want to follow
>     display-line-numbers-mode, you will need to heed that option as
>     well
>
>> 3. Leave the existing 'M-g g' bound to goto-line, but allow changing
>>    the numbering scheme using a prefix arg and a user option.
>
> I like this the best.

If making the current goto-line 'M-g g' more DWIM is not easy to do,
maybe really a user option could help with such choices:

- always use absolute line numbers;
- always use relative line numbers;
- follow the value of display-line-numbers-widen;
...

Also more explicit keys are needed, e.g.:

M-g l a   - with mnemonics: goto line absolute
M-g l r   - with mnemonics: goto line relative