Changes in branch ESP32-v3.0 (disable/enable BLE and Wifi)

Thanks! Looks good!

Do you think you could:

• Not do extern unsigned int jsVarsSize; (as someone might be tempted to change it on the fly!). Instead just make it an argument to jsvInit if VARIABLES_MODE_MALLOC is set?
  
• Don't add variables_mode or change scripts/build_platform_config.py, but instead just add DEFINES+=-DVARIABLES_MODE_MALLOC like this: https://github.com/espruino/Espruino/blob/ESP32-v3.0/boards/PUCKJS.py#L44
  
  

I'm happy to make those changes if you want me to though.