pkg/semtech-loramac: improve TX status management after sending a message

github: fix security bug template

cpu/saml21: extend and fix exti configuration for saml21 variants

cpu/esp8266: Fixes and improvements of esp_wifi netdev driver

Added a configuration for saml21g18a and fixes the configuration for samr30g18a

.github: add big warning signs about security bugs

sock_dns: correctly report too short messages

gnrc_ipv6_nib: use generated EUI-64 for ARO build and check

Checking by the send function that at least two maximum size Ethernet frames fit in the remaining heap before the LwIP packet buffer is allocated seems to increase stability. This can be caused by the fact that WLAN hardware interrupts allocate additional memory when receiving a frame during the send attempt.

tests: remove leftover test targets in test application makefiles

drivers/ltc4150: (Re-)implemented driver for the LTC4150 coulomb counter

The msp430 toolchain is missing an `fputs()` implementation. This commit makes
them use the `printf("%s", str);` instead of `fputs(str, stdout);`, which is
semantically equivalent (but has more overhead).

Implemented an example `ltc4150_recorder_t` implementation as a proof of concept
for the recorder API.

The LTC4150 is a coulomb counter (a.k.a. battery sensor or bidirectional
current sensor) that is used in the MSBA2 board and available for little money
as easy to use break out board.

The shell handlers of the old, depreciated and removed LTC4150 driver are still
in place. This commit removes them

sc_gnrc_ipv6_nib: check interface existence

doc: Update copywrites it include HAW