ieee802154: introduce constant for default PAN id
make: allow tagged RIOT_VERSION
cpu/samd21: add i2c periph implementation
make: `term` depends on `flash`

If you provide both `flash` and `term` as Make goals, then `term` needs
to wait for flash.
ip: check for null before ip_get_next_hop is used
doccheck: grep for all lines with a warning
Merge pull request #2124 from Kijewski/all-flash-term

make: term depends on flash
core: `sched_switch()` switch if not on runqueue

Fixes #1935.

`sched_switch()` should not only switch if the other priority is higher,
but also if the current thread was moved from the runqueue.
Don't evaluate inISR() if not needed
Merge pull request #1913 from Kijewski/issue-1910

make: allow tagged RIOT_VERSION
Merge pull request #2178 from cgundogan/ip_fix_null_check

ip: check for null before ip_get_next_hop is used
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