[Patch] Transparent and invisible transport ways

[Wolf01]

I was thinking for this feature since the transparency options got introduced.

I think roads and rails might be made transparent and fully invisible to ease the building of connections (an example is shown in the picture attached) and maybe to see why there's an edge around which don't allow to terraform in the middle of a city.

I usually build trenches like the one in the screenshot to make highways without placing the one way sign in every single tile, or between the rail and the road to deny level crossings, especially in cities.

In the screenshot, made before last modifications, you can see that transparent roads cannot be made since the road draws a full tile and is not possible to make only the road part transparent to show the slope under it.

Oh, I forgot to tell that the transparency works only for slopes, since there is nothing to show under a plain tile road, and this behaviour can be seen on the screenshot.

I think I'm not be able to finish it because it will get more complicate, if somebody have a better idea or wants to take it, here is the patch of all the work I've done.

[Vaulter]

Nice
But have such pic on coast lines

[Wolf01]

With that patch you will have this behaviour everywhere, I changed a little thing at the last moment after the screenshot.
The problem is that the transparent tile is 1 step over the non-transparent tile ('cause of optimisation), but since I need to change other things to make it work really as intended, I'll fix it later.
example: draw only the road overlay as transparent and not also the ground under it, but with original graphics I think it's not possible, I'll try to do something in the next days

[Vaulter]

constantly after save-load game - overmess transparent options