Add sunset and sunrise variables...

[stelas]

...for use in rule scripts as addition to time formulas. Calculation is based on geographic location which is configurable in advanced settings. Used algorithm is a tradeoff between computation time and accuracy. Both variables output a string value.

[TD-er]

That's some well programmed PR :)
I will merge it. We have to add some rules way to add an offset (in minutes I guess) to allow rules also operate on sunrise/sunset with some offset.
For example here in the Netherlands we don't have to switch on lights until 30 minutes after sunset, while I've noticed in countries like Greece this twilight time period to be a lot shorter.

[TD-er]

Also added some basic documentation to the wiki

[stelas]

Mhhh... another idea for a solution on the long run.

Currently variables are implemented either as strings or floats. So on actions e.g. "Clock#Time=All,%sunset%" is usable, but not a comparation like "%sunset%>18:00".

If all time variables are internally handled as timestamps and with some macros for string conversation, there would be no further distinction between both cases needed...

In this way, the suggested offset could be added or subtracted in the script.