tests: fix mutex_unlock_and_sleep pids

unittests: make: Fix unittests for branch changes

travis: remove comment obsoleted by #1742

Travis: reverted forcing travis to install `gcc-arm-none-eabi=4-*`

auto_init: Initialize link-layer addresses from CPU ID

Initial Stm32f4 spi driver

board/iot-lab_M3: cleanup of SPI and radio driver

cpu/board: cleanup for clock init on iot-lab_M3

- moved all board specific code to low-level driver calls
- moved some functions from the board dir into at86rf231.c
- added doxygen headers

- removed board specific code
- added interface definitions to board.h

- made config more versatile
- added pin configuration to spi_init()

Add backspace functionality in shell

rpl: mute RPL

make: only depend on directories that don't exist

pkg/Makefile.http: There were two recipes for clean.

Only add/replace changed members to the archive.

This fixes an error which was introduced by commit
346313bf

The timestamp of directories is updated when a file inside a directory
is changed.
Therefore, make decides a target needs to be rebuilt, whenever that
target depends on its parent directory, because the directory is
always newer than the file inside.

http://www.gnu.org/savannah-checkouts/gnu/make/manual/html_node/Prerequisite-Types.html

    Occasionally, however, you have a situation where you want to
    impose a specific ordering on the rules to be invoked without
    forcing the target to be updated if one of those rules is
    executed. In that case, you want to define order-only
    prerequisites. Order-only prerequisites can be specified by
    placing a pipe symbol (|) in the prerequisites list: any
    prerequisites to the left of the pipe symbol are normal; any
    prerequisites to the right are order-only:

         targets : normal-prerequisites | order-only-prerequisites

The were two recipes for clean. One of them is now "dist-clean"

core: Provide ssize_t in a common place

make: add objdump target + .PHONY missing targets from Makefile.include

drivers: import PIR motion sensor driver

Includes an application for manual testing.

boards:mega2560: add debug and debug-server targets

cpu: make stm32f{0,1,3,4} comply to UART0 module