Enables comparing achievements/statistics with another player.
After a call to this function, the INSPECTACHIEVEMENTREADY event fires to indicate that achievement/statistic comparison functions will return valid data on the given unit.
See also Achievement functions.
Signature:
success = SetAchievementComparisonUnit(unit)
Arguments:
unit- ID of a unit to compare against (unitID)
Returns:
success- 1 if the given unit is a valid unit. (Does not indicate whether the unit exists or can be compared against.) (1nil)