SYNOPSIS
        use PROCURA::XML::Entities;

        my $a = "Read "perlre" for explanation of '&'";
        my $b = decode_entities ($a);

        # $b will now be q{Read "perlre" for explanation of '&'}

        $c = encode_entities ($b);

        # $c should be the same as $a

        use PROCURA::XML::Entities ();
        $decoded = PROCURA::XML::Entities::decode ($a);
        $encoded = PROCURA::XML::Entities::encode ($a);