#100 mime magic for apple images is too generic

[galtgendo]

The way magic for application/x-apple-diskimage is described makes it prone to generating false positives.
I've came across a png image, that got identified as such ('BD' at offset 1024), leading to failures with gdk-pixbuf.

Short term solution: lower the priority, but perhaps the magic could be described better ?

[Henrik Stokseth]

Hi. I've tried to adress the issue you reported in commit a5a171. I've also commented on the issue in the commit message if you're interested in reading that.