Fixes:
- Change scripts in package.json (fixes #25).
- Remove unused submodule `c-src` (fixes #22)
- Normalizes casing of `Uint8` and `Uint16`
  throughout the code base (#29).

Features:
- add method `abort` to the returned promise of
  `sam.speak()` (#30).

Reorganization:
- Major refactoring to remove BREAK & END markers (#32).
- Cleanup test - remove dead code (#31).
- Cleanup and update dependencies.