MEDIUM: compression: add new "raw-deflate" compression algorithm

MEDIUM: compression: add new "raw-deflate" compression algorithm

This algorithm is exactly the same as "deflate" without the zlib wrapper,
and used as an alternative when the browser wants "deflate". All major
browsers understand it and despite violating the standards, it is known
to work better than "deflate", at least on MSIE and some versions of
Safari. Do not use it in conjunction with "deflate", use either one or
the other since both react to the same Accept-Encoding token. Note that
the lack of Adler32 checksum makes it slightly faster.