LuaState can push strings with embedded NULs.

This also marginally improves performance, since a strlen() isn't called (inside lua_pushstring()), the string length is stored in the AString object directly.
More MSVC warning fixes.
Removed a debugging log output in cPluginManager:AddHook().
Disabled an unneeded MSVC warning.

Also sorted the enabled warnings by their numerical code for easier searching..