Missing SNES 2BPP format

[racknae]

This is a pretty common graphics format in SNES games (usually used for graphics on the BG3 layer in Mode 1) so I'm surprised that this editor does not have support for it.

The "SGB border" format option allows you to view and edit the tiles and has the correct number of palettes, so I thought they might be the same, but the property byte differs between these two formats.