Inconsistent use of ISNT-ARENT

[eriktorbjorn]

Some actions use ISNT-ARENT to print either "isn't" or "aren't" depending on if it's a plural object or not, e.g.:

<DEFINE V-UNPLUG ()
     <TELL CTHEO>
     <ISNT-ARENT>
     <TELL "connected to ">
     <COND (<T? ,PRSI>
        <TELL THEI>)
           (T
        <TELL "anything">)>
     <ZPRINT ,PERIOD>
     T>

Some don't, though. At the very least not V-UNTANGLE, V-FEED, and V-POUR-FROM.