Official firmware enhanced

• add arduino-esp32 as a ESP-IDF component for easier development
  • porting some native but messy code to Arduino lib to avoid crash
• porting @cyberwisk's cardputer WebRadio as an App
  • using a modded version of ESP8266Audio to support https and chunked stream (like qtfm.cn)
  • ability to play radio in background when pressing HOME (G0), press ESC to fully exit
  • more radios (you can modify the radio list at (main/apps/app_radio/M5Cardputer_WebRadio.cpp)
• enhance SCAN, TIMER (renamed to CLOCK), SetWiFi App
• add SCALES and ENV IV App for the mini-scales and ENV IV m5stack sensors
• system enhance
  • WiFi will remain connected in background in default, open SetWiFi App again to turn off
  • use ESP-IDF's automatic sntp
  • enhance system bar
    • show battery voltage and current free heep size
    • add real feature to WiFi icon

M5Cardputer user demo for hardware evaluation.

ESP-IDF v4.4.6

git clone https://github.com/m5stack/M5Cardputer-UserDemo

cd M5Cardputer-UserDemo

idf.py build