Delete resources

[SiXoS]

There are currently very few deletions of pointers. There should be a thorough look through of destructors and positions where resources should be deleted.

Alternatively, smart pointers should be used instead of pure pointers.

[DunderRoffe]

I vote for using smart pointers.
Also in some cases like

bool compare(Obj* o1, Obj* o2) 

We should definitely use references instead of pointers as that eliminates the need for null checks.
By using const this also guarantees that the objects are not changed by the functions,

bool compare(const Obj &o1, const Obj &o2)