Remove pag-screen, since it's maintained elsewhere

pag-screen is now maintained in the SIPB locker (/mit/sipb/src/pag-screen/) and
on GitHub (https://github.com/sipb/pag-screen/). This version is now redundant,
and liable to become desynced (as it already has).

diff --git a/pag-screen b/pag-screen
deleted file mode 100755 (executable)
index c0c46e8..0000000
--- a/pag-screen
+++ /dev/null
@@ -1,62 +0,0 @@
-#!/usr/bin/env pagsh
-
-screen=`which screen`
-
-# Check for pre-existing screens.
-screenlist=`$screen -list | grep owl`
-if [ "x$screenlist" != "x" ]; then
-    echo "Found a pre-existing owl-screen session:"
-    echo "$screenlist"
-    echo "You probably want to reattach it instead."
-    echo
-    exit 1
-fi
-
-# Get AFS tokens for the screen session.
-# We are now in a new PAG (because of pagsh).
-# If you want to get tokens for other cells, list them in ~/.xlog
-aklog || echo "Failed to get new tokens"
-
-# Use separate kerberos tickets for screen. Even if we accidentally
-# (or intentionally) log out, screen and owl will still have tickets.
-NEWKRB5=/tmp/krb5cc_${USER}_screen
-
-# Copy the tickets we obtained on login to the screen tickets.
-KRB5CCNAME=`echo $KRB5CCNAME | sed 's/FILE://'`
-if [ "x$KRB5CCNAME" != "x" ]; then
-    cp $KRB5CCNAME $NEWKRB5
-else
-    echo "No tickets; not copying to new CC"
-fi
-
-# Now actually use the new tickets.
-KRB5CCNAME=FILE:$NEWKRB5; export KRB5CCNAME
-
-# Repeat for krb4 if appropriate.
-if [ "x$KRBTKFILE" != "x" ]; then
-   NEWKRB4=/tmp/tkt_${USER}_screen
-   KRBTKFILE=`echo $KRBTKFILE | sed 's/FILE://'`
-   cp $KRBTKFILE $NEWKRB4
-   KRBTKFILE=$NEWKRB4; export KRBTKFILE
-fi
-
-# Figure out which zephyr client to use.  Defaults to barnowl.
-if [ "x$ZEPHYR_SCREEN_CLIENT" = "x" ]; then
-    barnowl=`which barnowl`
-    if [ ! -x "$barnowl" ]; then
-       attach -n -q barnowl
-       barnowl=`athdir /mit/barnowl`/barnowl
-    fi
-    ZEPHYR_SCREEN_CLIENT="$barnowl"
-fi
-
-# Renew tickets and tokens.
-contrenew=`which cont-renew-notify`
-if [ ! -x "$contrenew" ]; then
-    zwrite $ATHENA_USER -d -m "$0: cont-renew doesn't exist on $(hostname)... Not doing renewals"
-    contrenew=/bin/true
-fi
-nohup $contrenew < /dev/null > /dev/null 2> /dev/null &
-
-# Name the screen pag so we can reattach the right screen later.
-$screen -S pag