scautoloc: add 'station-reference-time' option

[luca-s]

'station-reference-time' command line option allows to select stations that were active at a particular point in time. Very useful in playback.

This should close #23 #104 and #196

[jsaul]

Thank you very much for providing this code! I have been thinking about what would be the "best" solution to this issue. Being able to specify a reference time is certainly one way. I am sure the PR you provided works nicely. However, this reference time shouldn't actually be needed, because each pick that comes in *naturally* carries a reference time. This problem is that the initialization of the inventory is currently finished before the picks start arriving. I believe that the better solution to the problem would be a delayed inventory setup, with stations configured at runtime *after* arrival of the first pick of the respective station. Once we have a pick time we can use it to look up the correct epoch. The advantage of this would be that no configuration would be required at all, hence no command-line option needed. Does that make sense? Of course we might still run into a problem if the playback is very long (weeks, months) and includes the end of a station epoch and possibly the beginning of a new one. But this is a very minor problem compared to the current situation. I will look into this and see if I can make the required changes in the near future.

[luca-s]

@jsaul I agree, an automatic configuration would certainly be more user friendly. Though I believe that is a bigger change and I am afraid we will never see that patch landing in the code base.

[luca-s]

At the end of the day, running playbacks is something for advanced users, so it shouldn't be too much of a hassle to use a command line option to specify the station reference time. Just my 2 cents ;)

[luca-s]

@jsaul I saw your latest commit, beautiful! That should make this PR pointless.