Make list options translatable

Currently the options given for a list type field (e.g. on/off values for a checkbox) are never passed through the t() function, unlike the other field labels.

The perfect location for this would probably be in list_allowed_values() of field/modules/list/list.module.
In the case that an "allowed_values_function" does not exist we get original allowed values

$values = $field['settings']['allowed_values'];

and could apply t() to all values.

If we do it any later than we cannot be sure whether the allowed values came from an "allowed_values_function" and t() has been used already.
Moreover list_allowed_values() is being called for all options whether they appear in a form element or in a field formatter.