Return individual trimming parameters.

Related issue # and issue behavior

Issue #98: I would like to fingerprint each BME280 using the hash of the individual trimming parameters. I need a function that returns a copy of uint8_t m_dig[32].

Description of changes/fixes

The receiving array has to be supplied by reference. The function returns the reference to this array too (so not void, see below an example).

@mention a person to review

@finitespace, please comment.

Alternative was to return a struct. The advantage would be the parameters (dig_T1 - dig_T3, dig_P1 - dig_P9 and dig_H1 - dig_H6) could be added. But I don't need them now, so I prefer keeping it simple.

Steps to test

uint8_t parameters[32];
CRC32 crc;
uint32_t checksum = CRC32::calculate(bme.compensationParameters(parameters), 32);

Serial.printf("SensorID: 0x%08X\nHash(CRC32) of ", checksum);  
for (int i=0; i<32; i++) Serial.printf("%02X ", parameters[i]);  
Serial.print("\n");

Any outstanding TODOs or known issues

Adding an example (WIP)

finitespace / BME280