Large images crash the share extension

[katagaki]

Tested with a large illustration of size 5MB, shared from the Photos app.

Potential resolution:

• Unload list of albums to clear memory when starting import
• Create a new init() for Illustration that generates ID but does not save the image to disk, then manually save the image to disk from share extension

[katagaki]

Seems to be a remnant of when album covers were PNG, using up a lot more memory than required.