GM command to reload a specified global lua without a server restart.

This command expect the user to know wtf they are doing,
but has a default permission lv of 4 so that helpers or less experienced GMs do not mistakenly misuse it.

Use with caution, as some files ( like player.lua ) can cause you problems if you reload them using this.

I have disallowed player.lua and server.lua by default.
Merge pull request #454 from TeoTwawki/misc

GM command to reload a specified global lua without a server restart.