GetDateCodeStart
function GetDateCodeStart (const Key : TKey; const Code : TCode) : TDateTime;
GetDateCodeStart returns the start date stored in the Code.
Key must be the same key that was used to create the code or the code is considered invalid. If the code is invalid, 1 January 9999 is returned.
This routine is defined in the OgUtil unit.
Added in version 1.15.