[Commands] Add #setaltcurrency Command. (#1850)

* [Commands] Add #setaltcurrency Command.
- Add #setaltcurrency [Currency ID] [Amount] command to allow you to set a specific alternate currency to a value.
- Add Zone::GetCurrencyID() and Zone::GetCurrencyItemID() helper methods.
- Cleanup loops through zone->AlternateCurrencies.
- Utilize helper methods where necessary.
- Convert old methods parameters and return values from int to uint32 where necessary.

* Typo.

zone/zone.cpp

@@ -2421,10 +2421,9 @@ void Zone::LoadAlternateCurrencies()
 		return;
     }
 
-    for (auto row = results.begin(); row != results.end(); ++row)
-    {
-        current_currency.id = atoi(row[0]);
-        current_currency.item_id = atoi(row[1]);
+    for (auto row : results) {
+        current_currency.id = std::stoul(row[0]);
+        current_currency.item_id = std::stoul(row[1]);
         AlternateCurrencies.push_back(current_currency);
     }
 
@@ -2744,3 +2743,33 @@ DynamicZone* Zone::GetDynamicZone()
 
 	return nullptr;
 }
+
+uint32 Zone::GetCurrencyID(uint32 item_id)
+{
+	if (!item_id) {
+		return 0;
+	}
+	
+	for (const auto& alternate_currency : AlternateCurrencies) {
+		if (item_id == alternate_currency.item_id) {
+			return alternate_currency.id;
+		}
+	}
+
+	return 0;
+}
+
+uint32 Zone::GetCurrencyItemID(uint32 currency_id)
+{
+	if (!currency_id) {
+		return 0;
+	}
+
+	for (const auto& alternate_currency : AlternateCurrencies) {
+		if (currency_id == alternate_currency.id) {
+			return alternate_currency.item_id;
+		}
+	}
+
+	return 0;
+}