[New Feature] Auto-save on single-player mission start.

[CCHyper]

Description:

In Red Alert 2, the game auto-saves at the start of every single-player mission. These save files use a different filename format than user saves. They use the name of the scenario file rather than randomly generating a filename. For example, playing the first GDI mission, GDI01, would produce a save file called GDI01.SAV when you start the mission.

It would be ideal to use the same implementation that Red Alert 2 uses for the sake of simplicity. The only addition to the Red Alert 2 implementation would be to add an identifier "(Auto-save)" to the save file description.