#22 better support for & ampersand characters in uploaded file names

[SMacedo]

To fully support (listing them after upload) filenames with ampersands (&), uu_upload.pl, write_uu_file should escape some XML chars before writing the filename:

  $file_handle->print("   <\/post>\n");
    $file_handle->print("   <file>\n");

    # Write upload file info
    for my $file_slot (keys %uploaded_files){
            my $file_name = $uploaded_files{$file_slot}{'file_name'};

BEGIN PATCH

            $file_name =~ s/&/&/g;
            $file_name =~ s/</&lt;/g;
            $file_name =~ s/>/&gt;/g;
            $file_name =~ s/'/&apos;/g;
            $file_name =~ s/"/&quot;/g;

END PATCH

            my $file_size = $uploaded_files{$file_slot}{'file_size'};
            my $file_type = $uploaded_files{$file_slot}{'file_type'};
            my $file_status = $uploaded_files{$file_slot}{'file_status'};
            my $file_status_description = $uploaded_files{$file_slot}{'file_status_desc'};

            $file_handle->print("           <file_upload>\n");
            $file_handle->print("                   <slot>$file_slot<\/slot>\n");