Fetch the map hash

It'd be helpful to get the hash (or whatever unique id) of the current map in the gameinfo data.
Of course, the map is loaded based on what I supply as an argument to the game/API, but it'd feel much less flimsy and be more future-proof to get the actual hash of the map that the game ended up loading.

In my case I'd want this for caching: I spend something like 10 seconds generating all kinds of stuff from the terrain and unit information on game start, which I'd like to cache for next sessions by the map ID.
Especially important in realtime use, since that 10 seconds is subtracted from active play time.