BitMagic release v3.15.0

1. Implemented new API for right shift of bit-vectors
   bvector<>::shift_right()

2. Implemented fast aggregator SHIFT-AND for pattern searches.

3. New example for fingerprint based substring search (xsample04.cpp)
   with SHIFT-AND bitap algorithm.
   Tech. note: http://bitmagic.io/dna-search.html