Modify the use of normal pointers for smart pointers

[Fare9]

Take time for changing the use of common pointers to use smart pointers and avoid possible data leakages, dangling pointers, use after free, and all those kind of things. Think carefully where to use std::unique_ptr and where to use std::shared_ptr, former should be used for those variables that will not be returned by a method, used internally in a class and so on, latter should be used in all those types that are returned and used by other classes.