Put mux handling into I2CManager_NonBlocking.h to keep the native (controller-specific) drivers more simple.
Remove almost all but one of the static definitions, in preparation for supporting multiple I2C buses.
AVR Native (non-blocking) driver now supports up to 8 I2C Multiplexers, as does any controller that uses Wire for I2C.
Other native drivers will be updated in due course.
Change I2C addresses from uint8_t to I2CAddress, in preparation for MUX support. Currently, by default, I2CAddress is typedef'd to uint8_t.
MUX support implemented for AVR and Wire versions.
Timeout handling and recovery in loop() function now operative.
Start-up check for I2C signals short to ground added.
Initial I2C device probe speed up.
Possible infinite loops in I2C AVR native driver during fault conditions removed.
Corrections to I2C code:
1) I2CManager_Mega4809.h: Correct bitwise 'and' to logical 'and' - no impact.
2) I2CManager_Wire.h: Ensure that error codes from Wire subsystem are passed back to caller in queueRequest().
