Segfault in Vehicle class
Fix memory leak in Unit class

Related to blood created upon damage.
Found by Multipound/Memcheck

39 bytes in 1 blocks are definitely lost in loss record 252 of 1,100
78 bytes in 2 blocks are definitely lost in loss record 421 of 1,100
78 bytes in 2 blocks are definitely lost in loss record 422 of 1,100
95 bytes in 1 blocks are possibly lost in loss record 451 of 1,100
117 bytes in 3 blocks are definitely lost in loss record 493 of 1,100
975 bytes in 25 blocks are definitely lost in loss record 905 of 1,100
Ensure free of user mod list on startup
PhysicsBullet class to not leak memory

It was leaking lots of memory (upwards of 10 meg)
Fix leaks in GameManager class
Fixed memory leaks in Map class