Forgot to respangle the portraits using the new method.
Did so, and now the overall mod size is quite a bit more compressed without impacting quality.
Pushed the big button

Fixed missing text for Martian tiles
Fixed Mercury, mostly
Compressed files to make the mod smaller

Small update to make it compatible with the latest patch
Added two new galaxy sizes (Compact, 300 stars - Massive, 1200 stars) that allow for more aliens per-average than usual
More tweaks to Mercury, but it still has problems with seams and its polar cap, as well as a funky specular

Added custom model for Mercury

Reduced system size so that Pluto is within the game's navigation border box.

Minor fixes.

Changed it so that custom classes will not spawn outside of the original Sol system. (In theory)
Added and changed resource spawns for Sol system to include rare materials, and similar shenanigans.

Added localization for any bastards unlucky enough to actually spawn on Mars in games where you aren't playing as a Human.

Added system for custom planet classes to spawn resources.

Uploaded a Mod Image.