Crate supermemo2

Structs

Item	A struct that holds the essential metadata for an item using the supermemo2 algorithm.

Enums

Error
Quality	Enum representing the quality of an answer from 0 to 5. 0 - complete blackout. 1 - incorrect response; the correct one remembered 2 - incorrect response; where the correct one seemed easy to recall 3 - correct response recalled with serious difficulty 4 - correct response after a hesitation 5 - perfect response