bugfix: overflow of fmt index
Merge branch 'master' of github-ent.intra.douban.com:davies/beansdb
bugfix
check mtime of htree
skip empty files before scan bitcask
merge small data files into larger when optimizing
rollback debug config
bugfix
do not skip small data files
parallelized bc_close()
add debug info
bugfix
bugfix: divide by zero
bump to new version: 0.5.8
fix memory leak, make valgrind happy
check CRC checksum when scan data, skip broken data
skip broken data when optimizing
stop optimizing when shutdown
no error log when read fail, if optimizing
rotate current data file after optimizing

do not need restart after optimizing (GC) any more.