CORE: Added special case for single-string commands to allow spaces.
SCRIPT: Added exec GM command to execute raw Lua from chat.

WARNING: Having access to @exec can be potentially harmful! This can crash the server if used improperly! It is advised that you do not give access to this command to normal players / GMs. But instead, restrict the command to GM level 4. (By default this command requires Lv4 GM.)

I have coded this script to block the usage of os commands for safety purposes.