Setup export to Arduino library

[thirtytwobits]

Setup Cmake export to create an Arduino compatible library for publishing to Arduino library managers. Use platform.io as a proof-of-concept for release.

Requirements include:

1. all source must be under a src directory
2. generate a library.property file per https://arduino.github.io/arduino-cli/0.19/library-specification/
3. generate a keywords.txt file per https://arduino.github.io/arduino-cli/1.1/library-specification/#keywordstxt-format
4. create example sketches and publish to examples.