function ZipDeflate(filename, opts) {
        var _this = this;
        if (!opts)
            opts = {};
        ZipPassThrough.call(this, filename);
        this.d = new Deflate(opts, function (dat, final) {
            _this.ondata(null, dat, final);
        });
        this.compression = 8;
        this.flag = dbf(opts.level);
    }
Creates a DEFLATE stream that can be added to ZIP archives
@param filename The filename to associate with this data stream
@param opts The compression options