New attachment table no longer appended to content (while the old is ditched) : it actually is put in place of the old.

Now, files that have dots in their names are excluded if their extension is excluded. For example, image.preview.jpg won't be counted if 'jpg' is an excluded extension.

I added  an admin settings page to inform the admin about the download method selected. That page also shows the table of download count.

Added more access control granularity. With a new 'perm', users can or cannot access download count of files attached to nodes they have not authored.