pkg/oonf_api: fix conflicting types on msba2
unittests: core: add test_bitarithm_[ml]sb_all
Add test_ipc_pingpong
Add bitarithm measuring
core: faster bitarithm_msb
native: use `real_pipe()` and `read_close()`
dist/tools: add license checker

Creates file structure that maps files to licenses by grepping for
license patterns (patterns for licenses found in RIOT included).
Sets exit code to 1 if an unknown license header is detected.
Merge pull request #1181 from LudwigOrtmann/licenses

license checker
Merge pull request #1210 from benpicco/fix_oonf_msba2

pkg/oonf_api: fix conflicting types on msba2
Merge pull request #975 from Kijewski/issue-974

core: change in bitarithm implementation
Merge pull request #1322 from Kijewski/native-pipe-and-close

native: use `real_pipe()` and `read_close()`