Fix all warnings reported by clang

src/camera.cpp

src/camera.h

src/cguittfont/irrUString.h

src/clientiface.h

src/clientobject.h

src/clouds.h

src/connection.cpp

src/connection.h

src/content_cao.cpp

src/emerge.cpp

src/environment.cpp

src/environment.h

src/game.cpp

src/guiVolumeChange.cpp

src/guiVolumeChange.h

src/localplayer.cpp

src/localplayer.h

src/main.cpp

src/map.cpp

src/mapgen.h