I've finished the validation stuff for both ship relocating and population transferring. I also implemented the UI for ship relocating. For the screenshot, I temporarily disabled the validation stuff, aside from fuel range restriction. Green line is population transfer, blue line is ship relocation:
I'm putting the planet UI on hold now, since it's functional (can build buildings, can generate research points, can set relocation/population transfer). Next up on agenda is re-doing the fleet UI and adding space/cost/power values to technologies so that eventually I'll be able to re-do the ship design UI. After those two, colonization and the accompanying UI.
The pieces are starting to fall into place, and the game will soon be playable again!