Merge branch 'release-4.2' into fix/json-buffer-overflows

.gitignore

.travis.yml

Makefile.embedded

Makefile.help

Makefile.include

arch/cpu/arm/Makefile.arm

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/cc2538-def.h

arch/cpu/cc26xx-cc13xx/Makefile.cc13xx

arch/cpu/cc26xx-cc13xx/Makefile.cc26xx-cc13xx

arch/cpu/cc26xx-cc13xx/cc13xx-cc26xx-def.h

arch/cpu/cc26xx-cc13xx/cc26xx.ld

arch/cpu/cc26xx-cc13xx/rf-core/ble-hal/ble-hal-cc26xx.c

arch/cpu/cc26xx-cc13xx/rf-core/cc13xx-50kbps-tsch.c

arch/cpu/cc26xx-cc13xx/rf-core/cc13xx-50kbps-tsch.h

arch/cpu/cc26xx-cc13xx/rf-core/ieee-mode.c

arch/cpu/cc26xx-cc13xx/rf-core/prop-mode.c

arch/cpu/cc26xx-cc13xx/rf-core/rf-core.c