upgraded strings confuse Load()

[FGasper]

String stored internally as bytes:

> perl -Mstrict -w -MYAML::Syck -e'my $foo = "---\népée"; my $parse = YAML::Syck::LoadYAML($foo); print $parse;'
épée

String stored internally as UTF-8:

> perl -Mstrict -w -MYAML::Syck -e'my $foo = "---\népée"; utf8::upgrade($foo); my $parse = YAML::Syck::LoadYAML($foo); print $parse;'
épée

Since Perl applications don’t (normally) control a string’s internal representation, this library should define separate LoadBytes() and LoadUTF8() functions.

(This is the same problem as with CDB_File.)

[FGasper]

Also separate DumpBytes and DumpUTF8.

[FGasper]

Provisional workaround DumpBytes implementation:

sub DumpBytes {
    Data::Rmap::rmap_all(
        sub {
            if (ref) {
                if ('HASH' eq ref) {
                    %$_ = map { $_ && utf8::downgrade($_) && $_ } %$_;
                }
                elsif ('ARRAY' eq ref) {
                    $_ && utf8::downgrade($_) for @$_;
                }
            }
            elsif ($_) {
                utf8::downgrade($_);
            }
        },
        $_[0],
    );

    return YAML::Syck::Dump($_[0]);
}

[FGasper]

In fact … shouldn’t Load() always assume its input is bytes?