Add wcalc 2.4.1

Note that there are two different projects named 'wcalc' (modulo
case).  The one added here, whose name officially seems to be
'Wcalc' (http://w-calc.sourceforge.net) and something else named
'wcalc' (http://wcalc.sourceforge.net).  I don't know which was
"first".

I named this formula 'w-calc' only because the hyphen is in the
URL for its homepage.  The binary is called 'wcalc' and the
manpage is 'wcalc.1'.

I'd prefer to omit the hyphen because there's no formula
for the other project.  But the maintainers will decide what's
best.