sshscreen: add ServerAliveInterval=15

files/bin/sshscreen

@@ -1,3 +1,5 @@
 #!/bin/sh
 
-exec sshloop -t "$@" exec screen -dRU
+ServerAliveInterval=15
+exec sshloop -t -o "ServerAliveInterval=$ServerAliveInterval" \
+	"$@" exec screen -dRU