scfg: add "long name/short name" toggle in door mode.

When running scfg -iD and you go into message sub-boards, only the short name is displayed. There are times I'd like to see the long name list instead. Maybe add "t" to toggle between short and long name display.

Example:

[AmigaNet Sub-boards (21)]
 1: BBSNEWS AMY
 2: BBSSOFT AMY
 3: COMMS AMY
 4: COMS AMY
 5: FILE ANNOUNCE AMY
 6: HARD AMY
...

I'd like to see

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Amiganet: BBS Software Discussions
Amiganet: Comms
Amiganet: Communications Discussions
File Announcements
Amiganet: Hardware Chat