chippies: fix unintended growth through animal library

Inclusion of the library buffed the damage wild chippies do by 100%. This is unintended. Chippies grow (and get stronger) through sucking blood.
A commit that changes this behavior should address this directly. (This commit also makes chippies gain size a bit faster - as a compromise.)

The additional check in StartGrowth reduces overhead in the animals (and possibly plants) library. It is kept in this commit to give reviewers an example case for the check.

planet/Objects.ocd/Animals.ocd/Chippie.ocd/Script.c

@@ -93,7 +93,7 @@ private func FxClawingTimer(target, effect, time)
 		}
 		
 		// Grow and prosper.
-		if (GetCon() < 150 && !Random(10))
+		if (GetCon() < 150 && !Random(5))
 		{
 			DoCon(1);
 			DoEnergy(5);
@@ -273,6 +273,9 @@ private func LayEgg()
 	return o;
 }
 
+// Chippies grow (solely) via sucking blood (their size influences the damage they do).
+public func GrowthSpeed() { return 0; }
+
 local MaxEnergy = 10000;
 local MaxBreath = 10000;
 local NoBurnDecay = 1;

planet/System.ocg/Object.c

@@ -235,6 +235,7 @@ global func GetMaxBreath()
 // max_size = the maximum object size in tenths of percent.
 global func StartGrowth(int value, int max_size)
 {
+	if (value <= 0) return nil;
 	// Ensure max size is set and does not conflict with Oversize.
 	max_size = max_size ?? 1000;
 	if (!GetDefCoreVal("Oversize", "DefCore"))