Porymap renders full transparency for Covered/Split incorrectly

[GriffinRichards]

If transparent pixels align on both layers of a metatile using the "Covered" or "Split" layer type then Porymap will render the pixels using color 0 from the palette of the lower layer tile. This is not how they're rendered in-game. I'm not clear on whether this is always true, but in the examples below they are rendered in-game using color 0 of palette 0.

Porymap, pokeemerald (from left-to-right the columns are Normal, Covered, Split)

The area above in-game

Porymap, pokefirered (from Mt. Moon, no modifications)

The area above in-game