AplMode resource

New in 4.0 Some Unicode characters have multiple mappings to EBCDIC characters -- one for a "normal" character, the other for an APL-specific character.

When aplMode is set to true, the APL-specific mappings are preferred. When it is false, the "normal" mappings are preferred.

In x3270 and wx3270, the key combination Shift-Esc is mapped to a set of action(s) that includes setting aplMode.