Davies Liu: cache direntry in masterconn

reduce thread context switch to hold consistant

add cache info in master first, then add data in client,
remove data in client, then remove cache info in master
Davies Liu: fix bug in concurrent condition
Davies Liu: use getattr (cached) instead of opencheck when readonly
Davies Liu: no opencheck when create with readonly
Davies Liu: do not cache dir in 10 seconds after invalidate it.

invalidate dir cache after notify attr 10 times
Davies Liu: merge slow writes into larger one by every seconds.

delay first write by 1 second. cancel the delay when flush or end.
Davies Liu: skip blank line when parsing topology.cfg
Davies Liu: NoAtime: do not update atime and reduce ACCESS in changelog

merge patch from Travis Hein <marsairforce@gmail.com>
Davies Liu: do not report space when all changes < 0.5%
Davies Liu: refactor: fix hash collision in loop buffer
Davies Liu: use kqueue in master/matoclserv.c
Davies Liu: epoll in matoclserv.c
Davies Liu: refactor: move epoll/kqueue into mfscommon
Davie Liu: use epoll/kqueue in matocsserv
Davies Liu: bugfix: update maxtotalspace when cs register
Davies Liu: disable mmap: it will return -1 when failed, passert() will succeed
Davies Liu: bugfix: flush packet to fd (max)
Davies Liu: handle malloc failure
Davies Liu: fallback to poll when no epoll/kqueue
Davies Liu: bugfix