Added more things to the unrequire blacklist

There won't be much benefit in requiring these anyway, they are built into Lua and so won't be re loadable from file and won't save any memory.

Author: skyem123

unrequire.lua

@@ -16,8 +16,9 @@ local blacklist = {
 	["term"] = true,
 	["keyboard"] = true,
 	["table"] = true,
+	["string"] = true,
+	["math"] = true,
 }
-
 local function errprint(msg)
 	io.stderr:write(msg .. "\n")
 end