Fix RCSID's

Revert all previous TAILQ_NEXT() = NULL, changes, checks against
NULL vip's and removal of screens from queues. Instead introduce
a new screen_end1() function that can be used to clean screens that
a

Revert all previous TAILQ_NEXT() = NULL, changes, checks against
NULL vip's and removal of screens from queues. Instead introduce
a new screen_end1() function that can be used to clean screens that
are not associated with queues yet. Pointed out by chuq@

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Avoid repainting after screen has been destroyed.

- replace CIRCLEQ with TAILQ
- fix open-coded LIST code
- fix destroy screen bug (was not removed from list)

Apply our local changes.

Import nvi-1.81.6 + HEAD-2013-11-20 from git://repo.or.cz/nvi.git