Save games record more version & mod data

[ixnorp]

I've been reading the bug report forums a lot lately and I see a few questions pop up very frequently even when the save file is attached to the OP:

• What version did you start this map on?
• Did you migrate this map from version X to version Y?
• Have you used any mods?

Perhaps save files ought to record more information about this sort of thing in order to assist in debugging. For example what version & date/time the map was initially started under. Any time the map is migrated to a different version of Factorio record again the version + date/time. Record what mods were active when a game was saved (and the versions of those mods perhaps) and if the mods were later deactivated. Plenty of information of this variety could be logged with out adding much to a save file and may help out with the dev's debugging efforts.