lua binder improvments

modules/core_lib/ext/string.lua

@@ -16,11 +16,3 @@ end
 function string:trim()
   return self:match('^%s*(.*%S)') or ''
 end
-
-function toboolean(str)
-  str = str:trim()
-  if str == '1' or str == 'true' then
-    return true
-  end
-  return false
-end