自动加载时各个文件夹后缀
例如，classes目录为.class，则文件实际后缀为.class.php 注意，只有对EXT常理设置的后缀文件有效，默认情况下EXT=.php
默认值
array(6) ( "config" => string(7) ".config" "classes" => string(6) ".class" "controllers" => string(11) ".controller" "models" => string(6) ".model" "orm" => string(4) ".orm" "views" => string(5) ".view" )