returns the the index of n-th bit set in a bit mask counting from the right, for instance, in a mask ..0110 1000 , the 0th set bit(right-most bit set to 1) is at 3th position(starting at 0), 1st bit is at 5th position, 2nd bit is at 6th position etc..
Используется в AreaExposureMdfr::BleedingSourceCreateCheck(), PluginBase::InjectAgentsWithPlayer() и PluginBase::InjectAgentsWithPlayerCount().