Build as Universal 2 binary.

Update README to reflect recent changes and with new usage example.

Flatten get/set logic.

Merge pull request #36 from jtbandes/master

Support M1 Macs using DisplayServicesGetBrightness/DisplayServicesSetBrightness

Use even more SPI to get brightness and handle errors.

Update copyright date.

Use SPI on 10.12.4+ to set brightness since the documented way works poorly. (#21)

Update README.md

Update README.md

Update README.md

Update README.md

Update README.md

Update README.md

Update README.md