Refresh scheduling on specific days of the month

[mborzecki]

@niemeyer

That was specifically addressed in the proposal, hopefully in a clear way:

As a special case, the 5th week is considered the last one to hold the given day, so that specifying an event on the last Friday of the month, for instance, is done simply as fri5.

Read that twice and still found it a bit confusing, an example maybe, just to be sure that I got it right:

    November 2017   
Su Mo Tu We Th Fr  Sa
          1  2  3   4 
 5  6  7  8  9 10  11 
12 13 14 15 16 17  18 
19 20 21 22 23 24 |25|  <-- Nov 25 is both sa4 and sa5?
26 27 28 29 30       

Allowing to specify ‘last Friday’ actually makes sense, I’m just not sure about fri5.

Syntax wise, I think both proposals are close. Joining periods with .. is fine with me. Personally, I prefer using whitespace (implementation-wise we could probably support both) or having multiple --timer ... arguments in the command line.

I’ll give it another look in the morning, a rested mind may come up with more ideas

One more thing, somewhat unrelated to the syntax, but more to the execution. Is it possible to inhibit the timer from running? A use case that I’ve seen come up before is that the host/device is performing some critical task and while it’s being done no other functions that may have a negative impact (performance wise or just generally operation wise) are allowed. Should I bring that up in another thread perhaps?