Added 7zip's LZMA codec

[Tatu Saloranta]

Quick note: I added simple wrapper around 7zip's pure java LZMA codec.
While the way it is done is sub-optimal (package only allows
stream-to-stream operation; meaning driver must use intermediate byte
array input/output streams for buffering, to work in block mode), it
may not matter quite as much as with other codecs, since LZMA is
similar to bzip2 with respect to trade-offs: it has high compression
ratio, but relatively low speed.
If anyone wants to tackle converting library to support regular
streaming access that would be nice; but at least we can see how
compression ratio is compared to gzip/deflate and bzip2; and whether
performance exceeds that of bzip2 (allegedly decompression should be
bit faster).

-+ Tatu +-