[Suggestion] Allow pass-through missions.

[Nord]

I think, if mission map has exit points, and this is last stage, then aborting mission with x-com units standing on exits must force mission to be won.
Like "we get through these horrors to the freedom" etc.
On the other hand, this can give non-deserved loot to the player...
Maybe a flag can do the thing? Like "exitWin: true"?

[Meridian]

Isn't this already available?
I remember playing such missions in Area51 mod some years ago.