now with more clockyness

• numerous updates and improvements.
• selectable 12/24 hour mode without resetting
• seconds view mode

Known issue: long press for setting is sometimes missed. We are still working on the button responsiveness.

Thanks to jjmz and hachi.

Now works on STC15W408AS and similar variants.
(need to pass: STCGALPROT="stc15" make flash)

If using stcgal, you only need main.hex. If you are using STC-ISP, then you will also need eeprom.hex. Look at repo readme for more info.