Remove MCU dependent code from common/keyboard.c
USB initialize when plug-in during battery powered
Add power control of key switch board
Add keyboard LED control via Bluetooth
Add FET swtich for battery ADC
Improve rn42_task time resolution
Update MEMO and remove a build option to save flash
Monitor battery and alert low voltage
Fix rn42_linked() to use pullup
Add files missing for JP support.
Add initial setting of Linked pin
Add battery monitor and LED control
Add rn42_lined(): connection status(GPIO2)
Add flow control by firmware to serial_uart