use bsf
update benchmark  orz...
ntz switching eliminated
use dense map in benchmark
enbug
stack some debug..
stack is difficult...
some more
states_ should be indirect reference
append qsbr
untabify and quiet
use stack qsbr
persistent version of qsbr
it's tough bug..
untabify
some debug
direct bucket ok
fix build error in OSX 10.9 + clang-3.4