release 3.5.1-7
- make event timer more safety when user can cancel another timer in one timer;
- fp->read_ready should be set 0 in acl_file_read;
- use MD compiling options for all vc projects;
- v3.5.1-6: zlib upgrade to 1.2.11 from 1.2.8;
- v3.5.1-6: There's a better way to check if the given fd is socket, pipe or fifo;
- v3.5.1-6: ssl module supports SNI;
- more feature added and some bugs fixed.