LIC : change license from GPL -> 3 clause BSD

They promised me cookies!
BUG/PERF: Re-enabled loop short-circuiting in _refine_numba() by fixing typo.
Merge pull request #86 from nkeim/numba-refine-cleanup

BUG/PERF: Re-enabled loop short-circuiting in _refine_numba()
Merge pull request #46 from tacaswell/lic

LIC : change license from GPL -> 3 clause BSD
TST: Test several flat peaks where duplicates should be merged.
PERF: Refactor flat peak duplicate merging and margin detection.
CLN/BLD: No more C extensions.
PERF: new benchmark targeting local_maxima