Use enum weapon_type_t in more places
Use narrowly scoped loop variables in kconfig
Use accessor for most get/set object->id accesses
Mark various headers for C linkage
Move similar/main/kconfig.c -> similar/main/kconfig.cpp
Move similar/main/kmatrix.c -> similar/main/kmatrix.cpp
Move similar/main/laser.c -> similar/main/laser.cpp
Move similar/main/lighting.c -> similar/main/lighting.cpp
Move similar/main/menu.c -> similar/main/menu.cpp
Move similar/main/mglobal.c -> similar/main/mglobal.cpp
Move similar/main/mission.c -> similar/main/mission.cpp
Move similar/main/morph.c -> similar/main/morph.cpp
Move similar/main/multi.c -> similar/main/multi.cpp
Move similar/main/multibot.c -> similar/main/multibot.cpp