Should fix these memory leaks:
==22737== 14,598,040 (131,472 direct, 14,466,568 indirect) bytes in 2,739 blocks are definitely lost in loss record 3,124 of 3,126
==22737== at 0x4C2F1CA: operator new(unsigned long) (vg_replace_malloc.c:334)
==22737== by 0x90FE4B: LoaderDFF::loadFromMemory(std::shared_ptr<FileContentsInfo>) (LoaderDFF.cpp:443)
==22737== by 0x7BCC86: GameData::loadModel(unsigned short) (GameData.cpp:474)
==22737== by 0x7DF7BC: GameWorld::createInstance(unsigned short, glm::tvec3<float, (glm::precision)0> const&, glm::tquat<float, (glm::precision)0> const&) (GameWorld.cpp:144)
==22737== by 0x7DF44C: GameWorld::placeItems(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) (GameWorld.cpp:120)
==22737== by 0x758D38: RWGame::newGame() (RWGame.cpp:116)
==22737== by 0x786389: LoadingState::enter() (LoadingState.cpp:9)
==22737== by 0x75DC59: void StateManager::enter<LoadingState, RWGame*, RWGame::RWGame(Logger&, int, char**)::{lambda()#1}>(RWGame*&&, RWGame::RWGame(Logger&, int, char**)::{lambda()#1}&&) (StateManager.hpp:40)
==22737== by 0x758484: RWGame::RWGame(Logger&, int, char**) (RWGame.cpp:81)
==22737== by 0x747815: main (main.cpp:13)
This moves the object rendering logic into ObjectRenderer. This makes
GameRenderer a bit smaller.
There are some rendering logic decisions that haven't been brought
back yet since they may be better placed elsewhere.
