Make sharing debug logging easier for beta testing

[Abasz]

@JaapvanEkris I think based on user feedback it is desirable add proper logging to file that can be shared easily on github. The systemd logs are not that convenient. I am thinking a separate folder like Logs.

The logger (loglevel) that is currently being used has a plugin that would enable logging to a file, so there is not much that needs to be changed (https://github.com/infinum/loglevel-filesave).

Theoretically, it should be possible to create different logfile for rowing engine and general logging (that is a capability originating from the loglevel library). By just looking at the readme it may be possible to set the loglevel to different than the general one, enable debug logging even if the user set the loglevel to info. There are features that missing like, log rotation (these files with full debug logging would get huge over time, especially if there is a boot loop of ORM due to systemd). So moving to a more robust feature rich logger may be a better option on the log run, but swapping that out may be more work.

The new settings checker you added in PR#114 can add the default location automatically if user did not set it.

I have not tested the library as I am swamped with work, but I wanted to throw that in, so may be someone pick it up :)

[JaapvanEkris]

I like the integrated approach of syslog, as you see what is happening in the Pi. Especially when a housekeeping job is interfering with a too low prioritised GPIO thread, syslog will show that issues have arisen when apt-get did some updating.

Having it end up somewhere user specified increases degrees of freedom where people will have to look for their logs (where the location is recorded in those same logs....). And then you have to think about cleaning up the logs as well (which is managed by syslog quite well).

And doing a

grep npm /var/log/syslog

isn't that troublesome.