* Added 2 ffat partition schemes for 4MB modules + improved descriptions.
Existing format options were unclear on how much spiffs you were
getting. Also add missing 1MB App/3MB Spiffs split.
This addresses https://github.com/espressif/arduino-esp32/issues/1799
This makes it very clear what each option gives you, and also adds 2 options
to get ffat on 4MB chips..
* Added link to ffat howto.
* Update boards.txt
Add menu items for ffat on mhetesp32minikit board.
* Add partition table.
* Added ffat partition for 4MB ESP32 Dev Module.
* Added comment about partitioning schemes.
In Board.txt file added board revision submenu to distinguish the different revisions of the same board. By selecting different revision in the Arduino menu different value of the predefined macro will be applied which is used inside the pins_arduino.h file to make different defines and values for the specific revision.
In addition to this esp32-poe pin definitions is added ethernet power enable pin and also defined macro: BOARD_HAS_1BIT_SDMMC
* Add APB change callbacks and move cpu code to own file
* Properly set esp_timer and FreeRTOS tick dividers
* Improve updated devisors
* No need to update REF_TICK yet
* Add initial handling for UART baud change
* fix uartWriteBuf and uartDetectBaudrate
* trigger callbacks even when APB did not change
* toggle UART ISR on CPU change
* add XTAL freq getter and add cpu freq validation
* Support CPU frequency changes in I2C (#2287)
**esp32-hal-i2c.c**
* add callback for cpu frequency changes
* adjust fifo thresholds based on cpu frequency and i2c bus frequency
* reduce i2c bus frequency if differential is too small
**Wire.h**
* version to 1.1.0
* Implement clock change for the other peripherals
* remove bad CPU clock values from the menu
* Add note to CPU freqs that support WiFi and BT
* Add support to HAL for APB frequencies different than 80MHz
* Add support for CPU frequencies in the IDE board menu
* Switch to fast set_config
* Add method to uart so debug can be reassigned after apb frequency switch
* Return real APB frequency
* First commit of FFat library
* Fixed reboot loops if no fat present. Added CMakeLists
* Functionalize the partition checks
* Cleanup, especially in format
* Dont format if mounted. More wording cleanup
* 16M ffat should only be on 16M board
* Fix some casting issues that trip up the compiler when building as ESP-IDF component
* Add ttgo-lora32-v1 folder to variants folder
* Add ttgo-lora32-v1 info to boards.txt
* Add defs to pins_arduino.h for I2C OLED and SPI LoRa radio pinouts as per @stickbreaker
