When an application only includes Makefile.include without specifying
RIOTBASE and uses a `Makefile.local` file, RIOTBASE would use a wrong
default value and get the value of the directory where `Makefile.local` is.

build: remove hostname from RIOT_VERSION string

at86rf2xx: release framebuffer on recv with (len > 0) && (buf == NULL)

makefile.iotlab.single.inc.mk: add new supported nodes

The hostname does not provide any additional or necessary information to
the RIOT_VERSION string. On the contrary, some might consider the hostname
as personal information, which should not be exposed unsolicitedly.

nrf52840dk and microbit

gnrc_pktbuf: clarify doc of _start_write()

Resolves #10261

tests/pkg_cmsis-dsp: provide testscript

This PR sets the tranceiver in PLL_ON state to avoid corruption of the
data in the frame buffer and sets it back to the last state which the
 transceiver had before changing into transmit mode after the data is
read out. This is done to avoid data corruption when `_recv(...)` is
called to retrieve the buffer size and frame buffer protection is released.

boards/*: fix typo Feie => Freie

sys/ps: Remove unused include xtimer.h

 gnrc_pktbuf: add gnrc_pktbuf_reverse_snips() helper function

This allows for

a) testing the packet reversal properly in unittests
b) use it in other places than `gnrc_ipv6`'s receive function

examples/gnrc_networking/README: add make reminder, rm forced line breaks

sys/phydat: New phydat_fit API

 gnrc_ipv6_ext: move ipv6_ext_rh (partly) to GNRC

drivers/ds18: Add Maxim Integrated 1-Wire temperature sensor driver

gnrc_netif: Fix l2addr_len > 0, but no l2addr edge-case

at86rf2xx: Re-enable ack requests by default

boards/nucleo-l476rg: add I2C configuration

tests/tweetnacl: Move from unittests to regular test

Properly splitting the flags between netdev_ieee802154 and the at86rf2xx
driver had as side effect that the ACK REQ flag was no longer set by
default. This commit reverts the default settings by enabling it again
on startup. The current code calls the generic netdev setter to set the
flag.

Those return values are internal anyway, and they have the same intent
as the one provided by `gnrc_ipv6_ext_rh`.

tests/libfixmath: Add delay at start of test

makefile.iotlab.single.inc.mk: add new IoT-LAB supported nodes

The delay allows allows time for the `make term` to connect and start flushing the output buffer before the buffer overflows.

Stack size is changed from 4 times the default + printf to 5 times the
default stack size. Only on the lpc2387 this reduces the resulting stack
space. the test is not rerun for the lpc2387 and is untested.

Tests are disable for the Arduino. While they "might" work, it takes
around 8 minutes to complete the tests.

tests/driver_ds18: Add test application for DS18B20 sensor.

tests/driver_ds18: Add whitelist of boards