better autosave scheme

[mrvn]

At the moment the game is auto saved every X minutes keeping the last 3 saves. The number of saves can be changed in the config file but I think not from the GUI.

When I run around across train tracks or fight aliens it is easy to die and have to reload an autosave. There it's good if the autosave is not too old.
On the other hand sometimes you go off exploring or build a huge new chunk of factory and then decide it was a mistake. Then you want to load an autosave from 15-60 minutes ago.

Now one can configure factorio to save every minute and keep 60 savegames. But that's excessive. You only need like the last 3 minutes and then maybe 5, 15 and 60 minutes ago.

So my suggestion is to change when save games get overwritten. Keep the last 3 save games like it is now but also keep save games from increasing intervals. E.g. 5m, 15m, 1h, 6h, 1d, 1w, ...

My next suggestion is to change the name of the autosave files to <name of game>.<num>. The autosave from one game should not overwrite the autosave from another game.

My third suggestion is to (attempt to) autosave on crash of a mod. This might be useful to report a bug because loading the autosave probably crashes right there again. It would also allow one to disable a module and load the autosave and continue.