bugfix: zlog_reload can cause a crash by freeing memory used by zlog_spec_write_time.

see: https://github.com/HardySimpson/zlog/issues/7
bugfix: the last fix for zlog_spec_write_time is not right.
compile: makefile libzlog.a->lzlog
code: del useless code
bugfix: let OS release zlog_thread_t when thread exit, simple zlog_reload() and zlog_fini()
doc: typo
doc: smooth
compile: zlog-chk-conf no static, no need libpthread.a(which not exist on some OS)
bugfix: https://github.com/HardySimpson/zlog/issues/11
bugfix: kick pthread_key_delete, see https://github.com/HardySimpson/zlog/issues/9
test: make test_bitmap a little stronger
bugfix: using atexit to fix pthread_exit() not called in any thread
optimize: spec time cache for every thread
doc: remove %D in doc and test*.conf
compile: protect memset with if()check to suppress __warn_memset_zero_len compiler errors in some gcc>4.5.x
bugfix: check for time cache, see
https://github.com/HardySimpson/zlog/issues/13
doc: typo
doc: typo again
bugfix: the last fix for check for time cache is not correct
still https://github.com/HardySimpson/zlog/issues/13
bugfix: rebuild event cleanly, avoid cache pollution