BLE and battery icon replaced in Clock screen.
Added heartbeat and step icons in Clock screen.
Replace all labels in Menu by icons.
Add doc to generate new font.
- correctly write all bytes to flash
- check CRC
- Fix bug in notification : they cannot be sent from the control point handler (because it seems you cannot send a notification and a write acknowledge at the same time) using a timer (quick'n'dirty implementation to be improved)
- Improve dfu screen
- Reset if dfu image is correctly copied into flash and crc is ok.