Bug #35767 for Number-Format: error mixing LC_NUMERIC and LC_MONETARY

In the debian packaged perl 5.10.0 and Number::Format 1.52, the program foo.pl below produces Number::Format: {thousands_sep} and {decimal_point} may not be equal at foo.pl line 10 where I hoped it'd print "123.45". The combination in foo.pl of "C" for numeric and something european for monetary isn't as perverse as it sounds. In fact if you set LANG=de_DE then that combination seems to be the default perl starts up with! Nosing around I guess new() decides to use mon_thousands_sep as a fallback for thousands_sep, but in de_DE that's a '.' the same as the decimal_point of C locale. I think it'd be good not to mix LC_NUMERIC and LC_MONETARY values, better take decimal+thousands together as a pair in whatever fallbacks are used. Those initializations might be worsened by the way POSIX::localeconv() seems to omit "thousands_sep" altogether from its return when the thousands sep is an empty string, like in "C" locale. This sounds wrong to me, maybe there's a reason for it, I guess some care is needed not to be tricked by it though. But this is assuming an empty thousands sep is supposed to work. I see in the docs "... must each be one character", which I guess is not true of the "C" locale. If that really is a requirement then take this instead as a request to relax that :-), since I think no thousands sep is a fairly reasonable thing to do, I've dropped it for instance when running short of columns on a tty.