1. Set XXX_TAG static, remove extern XXX_TAG in uart.h/ledc.h/gpio.h
2. I removed uart_set/get_print_port() functions, these functions are not well tested, I removed them for now.
3. Modify some function names for uart_read/write_bytes
4. Modify uart_write_bytes and uart_write_bytes_with_break.
1. fix bug in ringbuffer.c:
When return an dummy item, free_ptr might exceed rd_ptr, so the write_ptr would overwrite rd_ptr in this case.
2. Delete UART tx task in buffer mode. UART ISR will copy the data from tx buffer to fifo.
1. Add a ring buffer for UART TX.
If the buffer size is set to zero, driver will not use a buffer. But we need a task to send data from buffer to fifo. I tried directly copy data in ISR, but the code looked too long for ISR.
2. Modify the format in uart.h
1. Use esp_log API for LEDC and GPIO code.
2. Modify some API return value.
3. Add ledc_set_pin() for LEDC
4. Modify typo in uart.h
Questions: In uart driver ISR handler, I used xxxFromISR , like xSemaphoreGiveFromISR, do those FromISR functions need to be put in IRAM?
