cpu/kinetis/rtt: clear TPR when writing TSR

net/nanocoap: add debug message for server

sys/crypto/aes: avoid UB by explicit unsigned integer promotion

cpu/nrf5x: handle multiple exti pins in gpio driver

Each pin is associated to a given GPIOTE channel

gnrc_sixlowpan: document submodules according to #8511

gnrc_lwmac: enable radio duty-cycle printing.

net/gcoap: make options buf macros configurable

examples/bindist: cleanup and fix formatting in README

gnrc_mac: add timeout module.

dist/tools/compile_and_test_for_board: add compile and test script

cpu/saml1x: add support for SAML10 and SAML11 MCUs (Cortex-M23)

cpu/atmega_common: refactor AVR libc code into module

cpu/esp8266: change of ETS task handling 

tests/posix_semaphore: private sub functions for tests libs

tests/periph_dma: add automatic testing of DMA over UART

cpu/esp32: fix of buffer sizes and length checking in esp_eth and esp_wifi

Disable optimization for this function only with CPU_SAML1X MCUs due to an internal crosscompiler bug

Add SAML10/SAML11 support through SAM0 because hardware IP are the same so reuse to avoid duplication

boards/stm32: revert forced use of dma feature in STM32 boards

During flash write access, the IROM cache cannot be used and is disabled therefore. During that time, ets_post crashes if a functions is called which is not in IRAM. Therefore thread_flags_set must not be called if IROM cache is disabled.

With the new ETS task handling thread, the stack sizes could be down sized.