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

Currently an interface's existence is not checked when it is supplied
by the user with the `nib` command. This can lead to assertion errors
as soon as the generated entry tries to resolve an address or route
generated with that command and the network interface not being found.

sys: add unaligned.h (header for alignment safe value-from-pointer functions)

uncrustify: change en/disable markers

doc: add reference to RIOT paper

.gitignore: exclude results directory

gnrc_icmpv6_echo: avoid crashing when pktbuf full

This directory is created by the compile_and_test_for_board script when ran from RIOTBASE and no custom value is specified

tests: provide unittests for gnrc_sixlowpan_frag/rbuf

boards/nrf52840-mdk: initial support

Once the packet buffer is full on heavy network load, gnrc_netif_hdr_build may return NULL. In that case, the following unchecked access to hdr->data leads to a crash.

drivers/enc28j60: fix of #9784

`gnrc_sixlowpan_frag` internally derives the offset value directly
from the fragment header, so for normal usage within GNRC this
assertion is redundant, but to make the tests of `rbuf_add` 100%
water-tide I added it.

The reason I put these unittests into their own application is that I
intentionally wanted to test this module very isolated.