0.5.2 release

Develop (#37)

- Thanks to Henk Holdijk for his improvements.
- fix #35, add **bool isConversionReady()**
- add **bool waitConversionReady(uint32_t timeout = INA226_MAX_WAIT_MS)**
- add constant **INA226_MAX_WAIT_MS**
- changed return type **bool setAlertRegister(uint16_t mask)**
- changed return type **bool setAlertLimit(uint16_t limit)**
- reorder functions in .cpp file to match .h
- remove not needed include from examples.
- update readme.md