Instead, we should multiply with the gold constant BitMixer#PHI_C64 (make it public).
This really makes a difference in the evenness of the value distribution. This is one of the secrets of the HPPC hashing. By applying this, we get multiple advantages:

  * lookup should be improved (less hash collision)
  * we can try to rehash at 3/4 occupancy because the performance should not be impacted until this point.
  * in case of hash collision, we can lookup linearly with a pos = pos + 1 instead of quadratic probe (lines 95 and 327); this may avoid some mem cache miss.
  * 
(same for the other hash method)