Minor fixes

1. Improve const correctness in a few places (such as `Container::getMaxStackSize()` -> `Container::getMaxStackSize() const`)

2. Use C++11 varargs for `I18n::get`, `Entity::newDoubleList` and `Language::getElement`

Minecraft.World/I18n.cpp

@@ -3,20 +3,3 @@
 #include "I18n.h"
 
 Language *I18n::lang = Language::getInstance();
-wstring I18n::get(const wstring& id, ...)
-{
-#ifdef __PSVITA__		// 4J - vita doesn't like having a reference type as the last parameter passed to va_start - we shouldn't need this method anyway
-	return L"";
-#elif _MSC_VER >= 1930	// VS2022+ also disallows va_start with reference types
-	return id;
-#else
-	va_list va;
-	va_start(va, id);
-    return I18n::get(id, va);
-#endif
-}
-
-wstring I18n::get(const wstring& id, va_list args)
-{
-	return lang->getElement(id, args);
-}