Moved euro sign to Alt-4 on UK and UK-based layouts. This involved moving the vulgar fractions to Alt-7,8,9.

Double upwards arrow (symbol for Shift on menus) added to assorted layouts,
as per diagrams. This still won't work in any alphabets other than UTF-8
because the International module doesn't recognise that character as being
in the official alphabets.

Version 0.64. Tagged as 'IntKey-0_64'