1) Rich is probably the best person to answer this question. You are right that it looks like the github hasn’t been updated for a year.
2) You are right that the sprinklers_pi program relies on wiringPi library, which isn’t available for Beagle yet. Theoretically there is no reason it can’t be made available for Beagle, it just seems that no one has made the effort to do so. If you would like to share your code, you can make a fork and release it under your own github repository I think.
As a side onte, I have been working on a common source for OpenSprinkler, and that will be able to run on both Arduino and Linux-based OpenSprinklers. It does not use wiringPi. Some details are explained here:
https://opensprinkler.com/forums/topic/what-is-the-status-of-zoneprogramming-in-ospi-comparable-to-the-arduino-version/#post-35150
3) The Google Calendar program is provided as a quick demo. When I was working on the Google Calendar demo, I thought it had a lot of potentials, because the calendar interface itself is a front-end, and it’s cross-platform. But then I realized it’s hard to integrate weather-based adjustment, and it loses many of the other features.
I am surprised that you are still able to use it, because last time I tried it didn’t work. I think Google has retired the v2 api, which is what the demo is based on. I haven’t yet figured out how to use the new api. But if you can still manage to get it running, please drop me a note and I’d be interested in knowing. Thanks.