You will probably want include version.c on savestruct or somewhere related to
it, so we can compare the version.

Us would probably end up splitting once again the save file, so it would have a
fourth file that store the savegame version. saveload.c would first try load
this file, and if the version is the same of the game's one, it will continue
the procedure. Otherwise, it will abort.
Or we could also add a fourth file with version, but instead of being processed
on load, being processed on menu. Processing on menu can have collateral effects
ie. high loading time before displaying the menu, etc.