GCW0: VIDEO: Fix flipped 512x256 => 320x240 downscaler (fnkyfish)
GCW0: VIDEO: Fix both normal and flipped 512x224 => 320x240 downscaler (galspnbl)
GCW0: GUI: Change preview loading.

  - Add support for .png and .bmp preview images
  - First check for clone preview, if absent load parent one