Rename Mob source files to CamelCase

Rename Cavespider.cpp to CaveSpider.cpp

Rename Cavespider.h to CaveSpider.h

Rename Magmacube.cpp to MagmaCube.cpp

Rename Magmacube.h to MagmaCube.h

Rename Zombiepigman.cpp to ZombiePigman.cpp

Rename Zombiepigman.h to ZombiePigman.h