Allow party to split at rest stops
So on the 4th depth down, you get to a rest stop, and can go up or down.
But right now the entire party has to go up or down. You can't have some people go to the up elevator and others to the down elevator.
Tonight, I had to use "leave party". Does doing this cost me anything? Do I have everything when this happens?
As I said, I was on the up, and the others were on the down.
We did not split. I had to go to menu -> party -> leave

You were doin' it wrong, because I've done it before.
I tried this twice before, actually, and neither times it worked. The first time, I was leaving, and I had to exit through the menu. The second time, two people were out of energy and tried using the elevator to Haven. They ended up just taking the down elevator, but using the menu that popped up to quit.
This is probably either a bug or an oversight. Either way, I think it should be fixed.
I haven't checked for sure, but I think if you leave through the menu, you lose everything you earned on that floor. Fortunately, at terminals, that isn't very much. I could be wrong, though. It might be only heat that is lost.
+1, since I want more minerals.
Only minerals and heat are lost by leaving via menu.
You lose minerals. You keep crowns and materials. Not sure about heat.
Ah, here it is.
http://wiki.spiralknights.com/Leveling_Equipment
>Upon successfully reaching the exit elevator of a level, your acquired heat is automatically applied to all of the equipment you are currently wearing.
So you don't keep it if you exit through the menu. Also interesting...
>A player that dies in a level will lose 30% of the heat they had collected so far. Should that player be revived by another player, the lost 30% will be given to the rescuer.

Party splitting at terminals is on the to-do list for sure.
You can do this already.
All the people have to be on an elevator for it to work, though.