Print manufacturing date as well as the factory-measured internal voltage reference value. These values are displayed by STC-ISP, too.
Implement option handling for STC8 series, based on STC8A8K64S4A12 reverse engineering. This mostly wraps up all important parts of the STC8 implementation. Interoperability was tested with STC-ISP V6.86O. v2: update documentation
What works: * Frequency calibration of internal RC oscillator * Flash/EEPROM programming What doesn't work yet: * Everything else