Method remove_if

src/fl/stl/list.h:457–466

    template<typename Predicate>
    void remove_if(Predicate pred) {
        iterator it = begin();
        while (it != end()) {
            if (pred(*it)) {
                it = erase(it);
            } else {
                ++it;
            }
        }
    }

    void reverse() {
        if (mSize <= 1) {