bugfix
lock(bc.write_lock) when changing bc->curr
fix bc->buffer_lock
improve gc: optimize data files modified before some time.

bugfix: deadlock when optimizing and close.
rotate recent modified data files.
bugfix: overflow caused by type convertion
bugfix: update version without new postion
re-generate with automake-1.11
bugfix: number of formats could be MAX_DICT_SIZE

add more error log when loading codec
bugfix: memory leak if load codec failed
bump version to 0.5.9
handle broken data in codec
add madvise() and posix_fadvise()

improve the filesystem buffer usage
use fadvise() with DONTNEED to release fs buffer

call fadvsise() every 64M when scaning
bugfix: dict_size overflow
bugfix: buffer overflow in list_dir with prefix
add stopme command

enable it by command argument -S