Support multi-level directory && fix sections coredump bug

[destinyac]

1、Support multi-level directory configuration： yaconf.directory = /tmp/yaconf/ ini file path： /tmp/yaconf/test/foo.ini use age： php7 -r 'var_dump(Yaconf::get("test/foo"));'

2、fix sections coredump bug eg:foo.ini

name=1 [student:name] test=2

3、configuration add yaconf.check_type if it is set to zero (default) will detect ini file's change by directory's mtime , otherwise will detect each file's mtime.