v1.0: Initial release.
v2.0: Added onboard 3.3V regulator to ensure enough current is available for the ESP-01 even when connected to an Arduino with a small 3.3V regulator. Added bias resistor to CH_PD line to enable normal run mode by default for ESP-01 modules with standard firmware installed.
v3.0: Added a "REFLASH" button to allow simple reflashing of the firmware on the ESP-01. Added a jumper for easy isolation of the reset line.