Merge pull request #749 from contiki-ng/release-4.2

.gitignore

.gitmodules

.travis.yml

LICENSE.md

Makefile.embedded

Makefile.help

Makefile.identify-target

Makefile.include

Makefile.tools

README.md

arch/cpu/arm/Makefile.arm

arch/cpu/arm/arm-def.h

arch/cpu/arm/cortex-m/Makefile.cortex-m

arch/cpu/arm/cortex-m/cm3/Makefile.cm3

arch/cpu/arm/cortex-m/cm4/Makefile.cm4

arch/cpu/cc2538/Makefile.cc2538

arch/cpu/cc2538/cc2538-conf.h

arch/cpu/cc2538/cc2538-def.h

arch/cpu/cc2538/dev/cc2538-rf.c

arch/cpu/cc2538/dev/cc2538-rf.h