Raw deflate/inflate functions (minimal size of compressed data)

It would be useful to add the ability to compress and decompress data in raw deflate-mode (without headers and wrapper) like the gzdeflate($string, $level, ZLIB_ENCODING_RAW) function in PHP:

```
$compressed = gzdeflate($str, $level, ZLIB_ENCODING_RAW);
$original = gzinflate($compressed);
```
Raw-mode (without headers and wrapper) provides the minimal compressed data size...