Added SKLVLO, SKLVLOCOED, updated all leveled list records

FNVLVLO, which was being used before, has `level` defined as a SINT16.  But,
Skyrim interprets that field as a UINT16.

New versions for Skyrim, applicable records updated.  Also refactored IsGlobal
and IsRank to GENCOED, made it easier to implement SKLVLOCOED.

Finally, updated LVLI, LVSP, LVLN to have COED data only on LVLI.