Hiss increases planetary happiness, by the same amount for natives and colonists. This formula used to read
Hiss_happiness_change = Min(Number_of_hissing_ships, MaxShipsHissing) * HissEffectRate
However, since PHost 4.1, HissEffectRate is arrayized. Therefore, in the general case, the Hiss_happiness_change is the sum of the HissEffectRate of the first MaxShipsHissing ships hissing at the planet (which can possibly belong to different players with different rates).
Note that hissing happens before taxation; after the hiss effect increases happiness, taxation will it bring down again.
