When importing pages from other apps, i.e. Paper by 53, it should import as a page not a scrap

[adamwulf]

the user can always cut out pieces if they want to scrap it. possibly show another section in the import sidebar too that holds previously imported images (?)

• [ ] give the user an option for scrap vs page when importing
• [x] import from Paper should save as a background to the page
• [ ] unload from cache when the page's assets unload
• [ ] confirm the trash manager plays nice with texture backgrounds
• [x] add a new page w/ the background if its a) from an app, and b) matches the screen bounds
• [x] otherwise, add a scrap like normal
• [ ] make sure adding new pages w/ backgrounds works in list view as well
• [ ] cutting out of the page should create a scrap w/ the background and fill hole w/ white
  • the filled path element needs to be set as [asErase:NO] instead of [asErase:YES]. this way the element will fill in with white wherever was cut out, and this'll also let future scraps cut from the same place show the same white background if cut out of the same hole.

related to: #1181, #1187

[adamwulf]

I should use the tiled PDF viewer in ZoomingPDFViewer to display the pdf as the page background.

ideally, i would:

• [ ] create new PDF with only that 1 page
• [ ] save the one page in the page's assets folder
• [ ] make page backgrounds abstract so that they don't rely on an image view if its not an image
• [ ] render that pdf with the TiledPDFView for the page background

[adamwulf]

fixed in #1614