[ok] Include approximate/actual conversion cost in plane info page

[sanabas]

If I look at a DC-6 on the UM, I see exactly how much maintenance costs for it, I see that there's the option for a freighter conversion. Likewise if I look at the new plane info, I see the costs for a brand new factory-spec plane. But I can't see, and as a returning player, have absolutely no idea, how much that freighter conversion will cost. Only way to find out is to lease the plane and look once it arrives. Which does me no good if it's too expensive to be useful, I've now got a plane I don't want to use.

So can there please be an extra line added, same as there is for maintenance, showing the conversion cost of a plane on the UM for whatever options it has, e.g. freighter conversion, hush-kit, winglets, etc.