* rmt driver initial version

* supporting conti mode plus interrupts

* using conitnous mode for sending more data

* working continous mode

* rmt driver cleanup after conti mode

* initial version of rmt driver

* adding a simple example

* adding channel and block locks

* modified of rmt interface for simpler/easier usage

* adding header sentinels, split interface to common and additional settings

* Fixes per code review + support for rx callback mode

* renamed internal structures and enums, fixed formatting

* cmake support for rmt

* refactored tx-conti interrupts to function to make it more readable

* added Tx and Rx examples

* added license headers

* minor updates per review

* used struct access, renamed defines, corrected diagram

* Add PSRAM init and malloc funtions

* Rebuild IDF libs

Fixes: https://github.com/espressif/arduino-esp32/issues/563
Fixes: https://github.com/espressif/arduino-esp32/issues/625
Source:
https://github.com/pcbreflux/espressif/blob/master/esp32/arduino/sketchb
ook/ESP32_int_temp_sensor/ESP32_int_temp_sensor.ino

Fixes: https://github.com/espressif/arduino-esp32/issues/384

WiFi and BlueTooth can now be started and stopped at will.
basic functions added to esp32-hal to start and stop the BT radio
SimpleBLE class added to show the most basic functionality
Example to show how to switch between BT, WiFi or Both

fixes: https://github.com/espressif/arduino-esp32/issues/193

Change is to not be mistaken with SD Card

Implementation for Timers 0-4 (no locks yet)

Fixes issue where switch will not properly trigger if Arduino is used
in IDF as component.
See
https://github.com/espressif/arduino-esp32/issues/83#issuecomment-265326
071

fixes: https://github.com/espressif/arduino-esp32/issues/72

IDF Options:
- Autostart Arduino (implements app_main)
- Disable HAL locks
- Set HAL debug level
- Auto-connect STA if configured (else will connect after WiFi.begin())

Fixes: https://github.com/espressif/arduino-esp32/issues/54

- Shorten filenames
- Add log_printf with mutex locking to play nice with Serial and two
cores