Initial support for C++ in gamecode, currently only compiles with -fpermissive
Make the gamelogic compile in C++

Involves a lot of casts, it could have been done in a smarter way, sometimes.
Merge branch 'master' into engine-upgrade/c++game

Conflicts:
	src/gamelogic/cgame/cg_consolecmds.c
	src/gamelogic/cgame/cg_draw.c
	src/gamelogic/game/g_active.c
	src/gamelogic/game/g_buildable.c
	src/gamelogic/game/g_cmds.c
	src/gamelogic/game/g_confidence.c
	src/gamelogic/game/g_weapon.c
We don't want -fpermissive when compiling C code – gcc complains.
Remove -fpermissive, was used for before d3278daba5d925b2 (Make the gamelogic compile in C++)