Fine-tune libtokyocabinet

- use the file tree database
- use compression
define the final kyotocabinet parameters

- type=filehash tree
- compression=gzip (shows effectiveness only for larger item numbers)
- small (reduce addressing size and limit database to a size of 16GB
- apow=0 (alignment power to multiples of 2^0=1 bytes)
- bucket number=30