BitMagic release v5.0.0

1. Fixed crash related to agressive -O3 optimizations on GCC

2. Implemented new algorithm: lower_bound search for integer in
   bit-transposed container: bm::sparse_vector_scanner<>::lower_bound()
   Documented as an API sample svsample07.cpp
   https://github.com/tlk00/BitMagic/blob/master/samples/svsample07/svsample07.cpp

3. New compressed serialization using Binary Interpolated Encoding.
   Tested on Gov2 collection it gives approximately 25% improvement in disk footprint comparing to
   previous version which was using Delta Elias Gamma encoder.
   New serialization is backward compatible, BitMagic will read old BLOBs.
   New serialization default is level 5. If you like to keep using Elias Gamma - use level 4.