pkg: provide sock_udp support for lwip

netdev2: unify doc

drivers: fixed doxygen groups

drivers/include/periph/spi: Typo fix

Fix typo in inline doc.

drivers/kw2xrf: adapt to netdev2

doc: net: replace doc references of conn with sock

    - use generic short and long address generator
    - defines in main header file
    - refine debug output
    - correct signed/unsigned warnings

    - add docu for structs, defines and functions
    - exclude drivers/kw2xrf/include/overwrites.h (vendor header)
    - add missing header guards

Adapt the kw2xrf driver for the netdev2 interface.
This patch also adds overwrites.h, the header provides overwrite
values for the kw2xrf PHY.

sys: net: gnrc: pktdump: add tcp_hdr_print

periph/hwrng: use void* buf for hwrng_read()

drivers/dht: updated auto-init + some enhancements

icmpv6: udp: fix formatter of checksum in header print functions

cpu/drivers: remove deprecated lm75a+lpc2387 I2C drivers

- unified auto-init to use same style as other SAUl devices
- make use of named return values
- added some asserts

Changes arduino-common to arduino-atmega-common.

tests/gnrc_ipv6_ext: update README.md

fmt: add print_byte_hex() helper

CI: murdock2: misc fixes

cpu/stm32_common/dist: prevent spi_divtable tool to add a trailing whitespace

pkg/u8g2: update version

sys/uuid: fix signedness warning