bug#3447: suggest minibuffer M-< go to start of text

[Juri Linkov]

>> This still doesn't work with <C-home>.  This can be fixed
>> by remapping beginning-of-buffer in the patch below.
>>
>> Like 'C-a' goes to the end of the prompt exactly like <home>,
>> there is no reason not to do the same for 'M-<' and <C-home>.
>
> Looks good to me.
>
>> Moreover, we don't add defcustoms for simple key bindings
>> because keybinding are configured with the help of define-key.
>
> Eli wanted the behaviour not to change by default.

Eli, do you think it would be better to change the default
because 'C-a' and <home> already go to the end of the prompt?

0.01% of users who for some unknown reasons might prefer it
to go to the beginning of the minibuffer, could easily rebind
the key back with define-key one-liner.