In TYPE_SAVE/TYPE_LOAD, show a confirmation.

AUTOSAVE/AUTOLOAD don't, SAVE/LOAD do.
Move some things around and simplify.
Default to saveName for AUTO LOAD/SAVE modes.

Maybe should for others, but at least these for sure.

Fixes #1017.
Merge pull request #1772 from unknownbrackets/savedata

Improve automatic save/load based on tests