cpu/samd21: add i2c periph implementation
doccheck: grep for all lines with a warning
tests: transformed tests/sha256 into an unittest
tests: transformed tests/bloom into an unittest
sys:net:routing:rpl made the number of routing entries configurable on compile time.
Merge pull request #2182 from phiros/tests_bloom_transform_into_unittest

tests: transformed tests/bloom into an unittest
Merge pull request #2180 from OlegHahm/doccheck_fix_grep_sed

doccheck: grep for all lines with a warning
tools/licenses: add revised 1c-BSD pattern used in utlist
sys/include: Include utlist for simple list operation defines
Merge pull request #2174 from fnack/utlist

sys/include: Add utlist to sys includes
boards,drivers,examples: unset ENABLE_DEBUG
Merge pull request #2181 from phiros/tests_sha256_transform_into_unittest

tests: transformed tests/sha256 into a unittest
Merge pull request #2186 from LudwigOrtmann/disable-debug

boards,drivers,examples: unset ENABLE_DEBUG
Merge pull request #2169 from BytesGalore/rpl_configuarbale_max_routing_entries

sys:net:routing:rpl allow setting the number of routing entries on comile time
sixlowpan: remove redundant assignment
sixlowpan: handle malloc error

The return value of malloc wasn't checked before, resulting in
possibly undefined behavior.
Merge pull request #2187 from LudwigOrtmann/sixlowpan-malloc

sixlowpan: handle malloc error
native: workaround for missing __builtin_bswap16

Implements a workaround for
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52624

This is present in current versions of ubuntu 12.04 and debian 7.7 (stable).
Merge pull request #2170 from LudwigOrtmann/native-bswap

native: workaround for missing __builtin_bswap16
make: migrate OS variable for COLOR_ECHO too