bug#43866: 26.3; italian postfix additions

[Juri Linkov]

>> I wonder why C-x 8 provides key sequences that are not mnemonic
>> and so hard to remember?
>>
>> Would it make sense to support exactly the same keys that are
>> provided by the X11 compose method?  I mean that are in the file
>> /usr/share/X11/locale/en_US.UTF-8/Compose
>> also available at
>> https://help.ubuntu.com/community/ComposeKey
>> and
>> https://cgit.freedesktop.org/xorg/lib/libX11/plain/nls/en_US.UTF-8/Compose.pre
>
> How about making a new input method for those?  It seems to me that
> C-x 8 is already too "fat".

Yes, a new method might be useful as well.  But since such method can't
be enabled all the time because such sequences as "= E" should be inserted
literally in normal circumstances.  So such method needs to be enabled
temporarily, and it takes more time to enable/disable it, while it's
useful only to insert a single special character sometimes, it would be
much easier to type some prefix key before typing "= E" to insert €
when such a need arises occasionally.