add chat message logging to game_lua_kernel
use setfuncs instead of register, so we can do partial define
move some callbacks (gettext, file ops) to lua kernel base
remove comment from dev concerned about a nonissue

read here: http://www.lua.org/manual/5.1/manual.html#lua_CFunction
When the C function returns with "1", all but the top entry are
discarded from the stack. If this function could be called again
and again without ever returning and without ever dumping the stack,
then there could be a stackoverflow, but in this case it's
not possible.