Add NanoPi support and test.
Currently the library supports RaspberryPi and NVidia Jetson Nano boards.
I successfully used the library on a NanoPi Neo board.
This commit includes all the changes that were needed to run two demos for the Waveshare 2.7' e-Paper HAT (B) described here.
The demos executed were: examples/epd_2in7_test.py and epd_2in7b_test.py.
I aimed to keep all the previous functionality unaffected.
@hnwangkg-ezio, is this pull request relevant to your vision for this project? How can I help you resolve it?
NanoPi support is now included in my fork of this project at https://github.com/kocielnik/e-Paper. In case you are interested, @technimad! :)