firmware@v0.2.0

Full Changelog: https://github.com/EnAccess/OpenSmartMeter/compare/firmware@v0.1.0...firmware@v0.2.0

• Refactoring the firmware code to be more modular (by @rtchuendem)
• Apply clang-format (by @dmohns)
• Add support for PlatformIO alongside Arduino (by @dmohns)