New feature
Not totally implemented. This feature will allow the user to browse his system, searching for image files, to send them.
This is a new Panel where the user can choose the folder he wants to browse. Then a (recursive) tree of this folder is display so that the user can browse it. Only images (currently jpg and png) are displayed. When the user clicks on a file, the image is displayed in a panel. He can right click on the file to send the image to piwigo.
At the moment, the first part of the feature is implemented (but not fully tested) : the display of the file tree and the display of the image on click. (the images cannot be sent).