Migrate the Disk Image and piped unarchiver to ARC.
Merge pull request #364 from MaddTheSane/ARC

Migrate the Disk Image and piped unarchiver to ARC.
Avoid direct ivar access for existing properties.
Convert remaining ivars to properties to avoid direct ivar access.
Enable -Wdirect-ivar-access; the codebase is now clean of this warning.
Quicker restart
Make SUDSAVerifier forward-compatible with Lion security
Deleted 10.6 code
Amend spurious copyright notice
Add contributors to the License.txt file
Fix potential memory leak
Double-check SecTransformExecute return value
Formatting
Removed unnecessary initializer
Removed unnecessary params
Removed unused method
Removed odd self=nil assignments
Rely on precompiled header
Apply clang-format rules
Removed UK initials from comments