adjust ICMP Timestamp output

adjust ICMP Timestamp output

* print TOS and/or TTL after the timestamps
* use the same output format with and without loop or count modes
* omit the comma in front of the timestamps with -a, --alive
* slightly extend man page description of --icmp-timestamp
* adjust existing ICMP Timestamp tests to output format changes
* add tests for some combinations of --icmp-timestamp with -a, -e,
  --print-tos, and --print-ttl