Factor out MersenneTwister32/64 utility functions into spire.random.mutable.Util.
Remove 2 blank lines
Add Well512a PRNG, deprecate Well512
Add Well1024a PRNG
Update doc for Util
Raise the treshold in GeneratorTest from 0.3% to 0.35%
Add Well19937a and Well19937c PRNGs
Fix doc for Well19937a and Well19937c
Fix formatting (remove spaces)
Fix performance issues in Well512a, Well1024a, Well19937a, Well19937c

Keeps the previous implementations in comments as they serve well for documenting the relationship between the variable names in the original algorithm and their expanded index mappings.
Add Well512a, Well1024a, Well19937a, Well19937c to RandomBenchmark
Add Well44497a, Well44497b; Update GeneratorTest and RandomBenchmark
Fix typo in RandomBenchmark
Remove tempering constants from Well44497a
Fix modulo premature optimization bug in Well19937a, Well19937c, Well44497a, Well44497b and raise the treshold in GeneratorTest from 0.35% to 0.38% to make 19937a/c pass.
Replace costly modulo operation with 2 ifs and addition/substraction
Remove old implementation (Well512)
Remove references to Well512 from RandomBenchmark
Merge remote-tracking branch 'dusank/topic/WELL'