Only one file is allowed to be deleted, and no directory is allowed to be deleted

只允许删除一个文件，且不能删除任何目录。

如何使用elFinder的bind绑定。

How to use elFinder bind.

其原理是绑定命令的动作前后。例如：rm命令。在删除之前则rm.pre，删除时rm

示例：

function rmCheck($cmd, $args, $elfinder){
    /**@var elFinder $elfinder*/
    foreach ($args['targets'] as $target) {
        if(is_dir($elfinder->realpath($target))){
            die(json_encode(['removed'=>'不允许删除目录！']));
        }
    }
    if(count($args['targets'])>1){
        die(json_encode(['removed'=>'不允一次性删除多个文件！']));
    }
}

$opts = array(
    'bind' => [
        'rm.pre' => 'rmCheck'
    ],
...