Add 'get_cpuid' command to return CPUID register (addr 0xE000ED00) value.
Add 'get_tempsensor' command to return internal temperature sensor on ADC_IN18.
Add 'get_vbat' command to return VBAT value (shared on ADC_IN18).
Add 'get_vref' command to return internal reference voltage on ADC1-IN17.
Add 'get_uid' command to return unique ID register (96 bits, Base address: 0x1FFF 7A10).
Add 'get_flashsize' command to return flash memory size (16 bits, Base address: 0x1FFF 7A22).
Add 'get_rstflags' command to return reset source (RCC_CSR). After read FW should write Bit 24 (RMVF: Remove reset flag). This will allow detection of unexpected resets and associated cause.