Implements genderless mons.

src/Library/CreatureData/CreatureSpecies.cpp

@@ -37,7 +37,9 @@ void CreatureSpecies::SetVariant(const ArbUt::CaseInsensitiveConstString& name,
 }
 
 Gender CreatureSpecies::GetRandomGender(ArbUt::Random& rand) const {
-    // TODO: Genderless creatures
+    if (this->_genderRate == -1) {
+        return Gender::Genderless;
+    }
     auto val = rand.GetDouble();
     if (val >= this->_genderRate)
         return Gender ::Female;