atmega_common: renames periph for atmega_common_periph

gnrc_uhcpc: fix dependencies

can/device: wake up device before getting/setting filters

boards/feather-m0: initial support

doc: increase GRAPH_MAX_NODES to avoid doxygen warning

tests: u8g2: fix i2c addresses.

drivers/si70xx: cleanup and use pseudomodules

Makefile.base: Add missing dep to RIOTBUILD_CONFIG_HEADER_C

Makefile.base: Fix indentation to two spaces

drivers: include board.h in default params files

packer: add dfu-util and bluepill udev rules

Assembly files '.S' are compiled with a subset of CFLAGS.
This means also `-include '$(RIOTBUILD_CONFIG_HEADER_C)'` so they should be
recompiled when it updates.

bluepill: dfu-util support

drivers: bmx280: include board.h for board parameters.

added the board.h include for:
- tsl2561
- jc42
- w5100

ringbuffer: add hint about tsrb to doc

Modified file doc header so that important info about usage and buffer
size show up on main API doc page instead of file doc page;
added comment in a couple of places to remind reader that buffer size
must be powewr of 2.

git: mailmap: deduplicate @jia200x

sock: specify invalid parameter error

pkg/heatshrink: fix fallthrough warnings

tests, thread_flood: update test script and output

makefiles: fix (and add) info targets

cortexm_common: Correct offset for hardfault stack

tests: pkg_fatfs: add periph_rtc to required features

make: reorganize makefile features