initial commit

Initial commit of atPeek and PNG and PVR QuickLook plugins used by
atPeek. Few issues:
- the app compiles and runs if PVRTexLib is installed into PVRUncrusher
plugin
- the FixPvrImageIfNeeded method in PVRUncrusher plugin needs to be
fixed
- atPeek needs to be updated to point it to the current iTunes folder
where iOS apps are nowadays installed.