public ByteBufferBitVector(final ByteBuffer b){
  this(b,0,b == null ? 0 : b.capacity() * 8);
}

public ByteBufferBitVector ( final ByteBuffer b ) { this ( b , 0 , b == null ? 0 : b . capacity ( ) * 8 ) ; }
ctor assumes that all bits in the buffer are used .
