Missing Features

[bsiever]

• [x] C code for more accurate clock / shim (test via disable behavior of shim temporarily)
• [x] Code for callbacks!
• [x] Review / update formats being used for strings returned
• [x] Testing, Testing, Testing (with radio and bluetooth)
• [x] Update comments and formatting / help
• [x] Tutorial / Docs / README.md updates
• [x] Icon
• [x] License
• [x] Use "pxt bump" to create a tagged release on GitHub
• [x] Get your package reviewed and approved https://makecode.microbit.org/extensions/approval

[bsiever]

Submitted for consideration.