Change atom.sh not to spawn a sleep process every second on --wait

As sleep(1) is not a bash builtin, every second a new process is spawed.
To  prevent this, the POSIX read can be used instead.
Since it is (required to be) a bash builtin, it is immediately killed along with bash unlike a longer running sleep would be.
In case stdin is e.g. /dev/null for whatever reason (this would break EDITOR=nano), sleep is still kept to prevent a tight loop.

atom.sh

@@ -149,6 +149,7 @@ trap 'on_die' SIGQUIT SIGTERM
 # If the wait flag is set, don't exit this process until Atom tells it to.
 if [ $WAIT ]; then
   while true; do
+    read
     sleep 1
   done
 fi