[MOD REQUEST]Fill cargo hold slider

[tandrej]

We should have an option to prevent traders from flying almost empty. Mule mods have that slider "fill % cargo hold", but it doesn't work quite well + it's implemented only for the "supply" option. It really should be part of vanilla for all types of trades. There shouldn't be any probability for a slow L trader with 45.000 m3 cargo hold to transport 1000 energy cells, unless ordered manually. I want my traders to hold position and ask for orders if they can't fill at least 80% of their cargo hold in 1-2 trades.