[open] New API functions IsVampire() / GetVampireStage()

[Baertram]

Thanks, have something similar in LibVampire I think, but have not updated it for a long while now

Hint
You can easeand speed-up such ifs

if (abilityId == VAMPIRE_STAGE_1) or (abilityId == VAMPIRE_STAGE_2) or (abilityId == VAMPIRE_STAGE_3) or (abilityId == VAMPIRE_STAGE_4) then

by the help of a simple table with key = abilityId and value = boolean true:

local vampireStages = {
 [VAMPIRE_STAGE_1] = true,
 [VAMPIRE_STAGE_2] = true,
 [VAMPIRE_STAGE_3] = true,
 [VAMPIRE_STAGE_4] = true,
}
if vampireStages[abilityId] then