The evtimer_msg test is expanded to also delete entries.
Furthermore the messages that are printed should now show
numbers that are very close (if not equal). Something like
this:
At 740 ms received msg 0: "#2 supposed to be 740"
At 1081 ms received msg 1: "#0 supposed to be 1081"
At 1581 ms received msg 2: "#1 supposed to be 1581"
At 4035 ms received msg 3: "#3 supposed to be 4035"
The function evtimer_print is also called to show the
intermediate status of evtimer entries.