Implements critical calculation, fixes some library pointers being unset, causing segfaults.

tests/TestLibrary/TestLibrary.cpp

@@ -52,7 +52,8 @@ static TypeLibrary* BuildTypeLibrary(){
 static BattleLibrary* BuildLibrary(){
     auto l = new DataLibrary(LibrarySettings(100, 4), BuildSpeciesLibrary(), BuildAttackLibrary(),
             BuildItemLibrary(), BuildGrowthRateLibrary(), BuildTypeLibrary());
-    auto battleLib = new BattleLibrary(l, new BattleStatCalculator());
+    auto battleLib = new BattleLibrary(l, new BattleStatCalculator(), new DamageLibrary(),
+            new CriticalLibrary());
     return battleLib;
 }