Allow most libraries to reserve capacity for their database.

src/Library/GrowthRates/GrowthRateLibrary.hpp

@@ -12,8 +12,11 @@ namespace CreatureLib::Library {
         std::unordered_map<std::string, GrowthRate*> _growthRates;
 
     public:
-        ~GrowthRateLibrary(){
-            for (auto gr: _growthRates){
+        GrowthRateLibrary(size_t initialCapacity = 10)
+            : _growthRates(std::unordered_map<std::string, GrowthRate*>(initialCapacity)) {}
+
+        ~GrowthRateLibrary() {
+            for (auto gr : _growthRates) {
                 delete gr.second;
             }
         }