CLI comes up in legacy "list" mode if neither stdin or stdout are a tty, or

CLI comes up in legacy "list" mode if neither stdin or stdout are a tty, or
if "--compat 20251114" or earlier is specified, or if "--batch" is used.
New modes "batch" and "tty" select either legacy "list" mode or the newer
"qbox" mode with limits.
Make CVS output compatible with legacy.  Break out ".import" into a separate
subroutine in anticipation of forthcoming improvements.  General code
cleanup.

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