Doesn't remove "read only" files and doesn't give any feedback that it can't

[dexter86]

Steps to reproduce to best see this:
1. create a new folder
2. copy two images to it
3. set those two images to "read only" in windows' explorer
4. open one of those images in xnview
5. delete it

Xnview shows confirmation dialog, you click Yes, it opens next image, you THINK it removed the previous one, but no, it's still there. You can now "mash Delete and Enter" and it will just go through those images in a loop.

Ideally there should be additional configuration option in "File operations" how to handle "Read only" files, let's call it "also remove read only files". And when a file is "read only" and that option is not checked, then there should be an information returned to user that it can't remove that file because it's "read only". And if that option is checked, then it should remove that file (IrfanView does that).