Added hook: post file upload

[prookie]

After successfully uploading a file in the panel, the callback function
stored in kirby option variable ‚panel.upload.post‘ is called with the
File object of the newly created file as well as the upload POST data as
arguments (mainly to get access to the original filename in my case)

[prookie]

In my case I used it to save the original file name of the uploaded file in the corresponding meta data of it.

config.php:

c::set('panel.upload.post', function($file, $uploadData) {
    if( is_callable(array($file, 'update')) )
    {
        $file->update(array(
            'originalfilename' => $uploadData['name']
        ));
    }

    // another option: $file->rename(...); etc
});

[bastianallgeier]

We are currently working on a global hook system. So I'm afraid I have to finally close this.