SparkyMK2 v0.3.0

Added

• Screens tab: edit a project's startup animation and screen saver, and write them to the
  device. Load a PNG, JPEG, GIF, WebP or BMP and convert it with a choice of dithering,
  threshold, brightness and contrast, or draw the 128 × 64 pixels by hand. The image each
  slot held before the app first changed it is kept, so it can be put back.
• sp404 screens, sp404 export-screen and sp404 import-screen do the same from the
  command line.