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`
This reverts commit 7074f35e4b.
7074f35e4b
This is one of the first commits in a plan to remove all `using namespace std;` lines in the entire codebase as it is considered anti-pattern today.