- added support for BQ40Z80 based battery
- added performance counter for interface errors
- added SMART_BATTERY_INFO mavlink message
- general code cleanups and optimization
- fixed: void flooding the log in case of interface error
- fixed: using _batt_startup_capacity instead of _batt_capacity for discharged_mah
- update: read manufacture_date
- update: get _cell_count from parameter and not const 4
- update: avoid re-reading data that has already been read and stored on class already
- currently the battery type defined by BAT_SMBUS_MODEL parameter and not by auto detection