Use shared_ptr in &Engine::AddWorld() fn

[claireyywang]

I think it might be a better practice to create shared_ptr instead of creating local object.

[iche033]

The changes look fine. Just curious, was this causing a problem? I think the original intention was that the insert call should make a copy of world so therefore it's safe for the local variable to go out of scope.

[claireyywang]

The changes look fine. Just curious, was this causing a problem? I think the original intention was that the insert call should make a copy of world so therefore it's safe for the local variable to go out of scope.

There wasn't any problem. I've just been reading about C++ and wondered if using shared_ptr would prevent any future issues. If it's good as is, I'd be fine closing this PR. What do you think? @iche033

[iche033]

ok sounds good. In that case, we could make worlds just store shared ptr? I saw that Entity's children is now using map of shared ptrs now so we could be consistent here

[claireyywang]

@iche033 friendly ping for visibility. I addressed the previous comment. Ready for another round of review whenever works the best for you. Thanks!