Extricate "extra attribute" code parsing enablement from global settings

For example, RIP terminal user should be able to view messages containing pipe codes.

Likely, use separate P_ mode flags for each extra attribute code-type and then maybe have (reuse) a global setting just for display/menu files, but message-bases should have their own separate setting for each extra-attribute code (e.g. pmode flags, which are already settable per sub).