Some specialcasing is warranted to get sensible messages.

Fixes #2532

stdin-fd is dead, it takes more than "break;" to get out of a
switch-in-a-loop.

Also: Make ansi-sequence problems fatal, and render unknown control
chars as '?'

I owe the next round Geoff.

... otherwise we will hit the WRONG("Wrong admin health") in VDI_Healthy()
for std.healthy().

Ref: https://github.com/nigoroll/varnish-modules/issues/5

Yes, evil things are afoot.

sizing VSMW clusters.

Fixes	#2535