
Appendable Screen Images Format v2
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Offset	Size	Name
0	4	Border ID (constant: 0x789B4987)
4	4	Number of images
; Below is repeated per image
n	4	Total size of image data (include headers)
n+4	24	Title of image, null terminated
n+28	4	Size of tiles
n+32	???	Tile data; lz77 vram safe compressed
n+???	32	Palette in AGB format (ie, 0BBBBBGGGGGRRRRR), 2 bytes per entry, 0 is junk
n+???	???	Screen map; lz77 vram safe compressed


Tile Data
---------

All tiles use palette 14 (0xE) and start at video ram offset 0x500 (font number 0x28).
This means that all tiles should have 0xE028 added to them.  Note, there is only enough
room for about 240 tiles per image.  Also note that doing a simple search for mirroring
and setting the appropriate bit (10 for horizontal, 11 for vertical) wouldn't be a bad
idea, where possible.

Palette
--------

Up to 15 colors can be used.  Color 0 is always transparent, so is not stored/loaded.

Screen Map
--------

The screen map is composed of 32x20 tiles.  The rightmost two tiles are not ever shown
and can be chosen to be any value (choosing one to increase compress would be advised).
The center of the visible screen is transparent.  This means the box (5,1)-(25,19) should
be filled with a "transparent" tile.  The simplest viable candidate is 0x0120, the same
tile used for the space in the text display.
