Fix a bug where ::warning() was called with a va_list argument instead of an actual vararg list. Also cleaned up the format for warnings. (Previously some would start with "warning - warning - Warning:" which was a bit redundant)

module tangotests.mem3;

void main()
{
    int[] arr;
    arr ~= [1,2,3];
    assert(arr[0] == 1);
    assert(arr[1] == 2);
    assert(arr[2] == 3);
    delete arr;
    assert(arr is null);
}