I am not sure that the save-in-battlescape feature would be welcome in the standard release. Anyone is welcome to modify the game and release a patch for the code, or an updated installer.
That's just the thing so many people seem to be missing the point of. Those of us that need a save in battle feature are ones who are just to busy with real life to sit and play through an entire map in one sitting. (some of the maps later on in game can take 45-60 minutes or longer on harder difficulties)
Now if we're too busy to play though a battle map in one sitting, where are we supposed to find the time to learn how to code an auto-save feature into the game, let alone actually code it?