Performance improvements

[SaveTheRbtz]

In this PR:

• Switch to faster hash

name          time/op
Murmur/1-8      2.68ns ± 1%
Murmur/4-8      3.45ns ± 1%
Murmur/8-8      4.70ns ± 0%
Murmur/16-8     6.19ns ± 0%
Murmur/32-8     10.6ns ± 0%
Murmur/50-8     16.3ns ± 2%
Murmur/500-8     202ns ± 0%
XXH3/1-8        2.53ns ± 2%
XXH3/4-8        2.51ns ± 2%
XXH3/8-8        2.45ns ± 1%
XXH3/16-8       2.35ns ± 1%
XXH3/32-8       3.16ns ± 0%
XXH3/50-8       4.87ns ± 5%
XXH3/500-8      38.6ns ± 1%

• Switch to faster sort

  
  name      old time/op    new time/op    delta
  Build        121ms ± 2%     101ms ± 3%  -16.14%  (p=0.000 n=10+10)
  Table       36.7ns ± 2%    28.1ns ± 2%  -23.35%  (p=0.000 n=9+9)
  TableMap    74.2ns ± 6%    63.9ns ± 3%  -13.95%  (p=0.000 n=10+9)

name old alloc/op new alloc/op delta Build 32.7MB ± 0% 32.7MB ± 0% +0.02% (p=0.000 n=7+9) Table 0.00B 0.00B ~ (all equal) TableMap 0.00B 0.00B ~ (all equal)

name old allocs/op new allocs/op delta Build 302k ± 0% 302k ± 0% +0.07% (p=0.000 n=10+10) Table 0.00 0.00 ~ (all equal) TableMap 0.00 0.00 ~ (all equal)

Ref: https://github.com/cespare/mph/issues/3