1. Support built-in ADC for I2S.
2. Modify code of ADC, made no change to the original APIs.
3. Add APIs in I2S:
esp_err_t i2s_set_adc_mode(adc_unit_t adc_unit, adc1_channel_t adc_channel);
4. Add I2S ADC/DAC example code.
5. add old-fashion definition to make it more compatible
6. replase spi_flash_ APIs with esp_partition_ APIs
7. add example of generating audio table from wav
8. change example sound
1. add sens_struct.h
2. add definition of RTCCNTL and RTCIO
3. modify touch pad examples
4. update example code.
5. add comments add option in menuconfig
6. fix issue that pad index 8 and 9 are mismatched
7. add touch_pad_read_filtered() api to get value filtered by iir filter
8. modify touch pad isr func
9. Make the items in perihperal.ld in the sequence of address
10. delete Kconfig for touch pad
11. add touchpad filter APIs to adjust the filter
12. add touch_pad into index.rst
13. add touch_pad in Doxyfile
14. add touch_pad.rst
1. Name change from chopper to carrier, block diagram update, minor changes to example codes
2. mcpwm_reg.h changed, brought uniformity in comments, worked on suggestions, duty to accept float. Some name changes!
3. Minor readme changes and Indetation
4. Minor change: move mcpwm_reg.h and mcpwm_struct.h to new path
5. Minor change: addition of BLDC example code and Readme
6. Name changed from epwm to mcpwm
7. Improve the reg name in mcpwm_struct.h
8. Name change chopper>carrier, deadband>deadtime
