Bug 410868

SUMMARY
During the sprint Dmitry me and Stefan had a discussion about snapshot feature in Krita. Stefan and I wished that snapshots could be created automatically in additon to the manual snapshots that we can make

The snapshots created automatically would have these features
1) configuration in settings for time interval preferably more than 30 minutes
2) auto-deletion of older snapshot but leaving the manual snapshots alone.
3) automatically created snapshots would have timestamps suffixed before their name

advantages - 
1) This will help to tackle the limited number of undos one has since now he can have snapshot for the time when undo is cleared.
2) This will help someone to start over the painting from X hr/min ago (for example how you can go back 1 hr ago when editing a file in vim)