Using xxx_periph.h in whole IDF instead of xxx_reg.h, xxx_struct.h, xxx_channel.h ... .
Cleaned up header files from unnecessary headers (releated to soc/... headers).
1. separate rom include files and linkscript to esp_rom
2. modefiy "include rom/xxx.h" to "include esp32/rom/xxx.h"
3. Forward compatible
4. update mqtt
Because of errata related to BOD reset function, brownout is handled as follows:
- attach an ISR to brownout interrupt
- when ISR happens, print a message and do a software restart
- esp_restart_nonos enables RTC watchdog, so if restart fails,
there will be one more attempt to restart (using the RTC
watchdog)
