[boskid] Half diagonal rail should cost 2 rails

[half a cat]

A half-diagonal rail is twice as long as a straight rail for the same cost, so zig-zagging railways are cheaper than straight ones. I suggest to make half-diagonals cost 2 rails for balancing purposes. It would be like how curved segments cost multiple rails.

[IvanScemer]

Yeah, I agree, because even visually a half-diagonal rail looks like 2 straigt ones. And zigzagging is almost twice as cheap

[boskid]

Actually this was a bug because elevated half-diagonal rails would cost 2 rail items while ground ones were buildable by 1 rail item. This will be fixed 2.0.13.