Starting multiple maps
Working on multiple maps
Merging in master
Creating challenge-orientated multiple maps
Merging in master
Fixed segfaults
Working to remove all shared pointers and moving to id handles
Objects and maps are fully destructed on closing a challenge
Adding in player class to maintain player state across challenges and cleaned up challenge construction
Game finally exits cleanly. Fixes #71. Fixes #70. Fixes #62
Merge branch 'multiple-maps'. This merge brings in the changes to get
the game to exit cleanly. Further testing is needed on machines other than mine
to check this is the case.