benchmark of "Replace with flexible CSV parser"

gistfile1.txt

```
$ rake
Run options:

# Running tests:

Finished tests in 1.893467s, 224.9841 tests/s, 4058.1642 assertions/s.
426 tests, 7684 assertions, 0 failures, 0 errors, 0 skips

ruby -v: ruby 2.5.3p105 (2018-10-18 revision 65156) [x86_64-darwin17]
$
```


```
$ ruby benchmark/parse.rb
# https://github.com/284km/csv/blob/scanner/benchmark/parse.rb

# after Replace

Warming up --------------------------------------
            unquoted     3.000  i/100ms
              quoted     2.000  i/100ms
     include col_sep     1.000  i/100ms
     include row_sep     1.000  i/100ms
        encode utf-8     2.000  i/100ms
         encode sjis     3.000  i/100ms
Calculating -------------------------------------
            unquoted     38.104  (± 7.9%) i/s -    192.000  in   5.073586s
              quoted     21.494  (± 9.3%) i/s -    108.000  in   5.076472s
     include col_sep     13.366  (± 7.5%) i/s -     66.000  in   5.018670s
     include row_sep      6.601  (± 0.0%) i/s -     33.000  in   5.009123s
        encode utf-8     31.722  (± 3.2%) i/s -    160.000  in   5.053156s
         encode sjis     31.669  (± 3.2%) i/s -    159.000  in   5.029365s

# before Replace

Warming up --------------------------------------
            unquoted     3.000  i/100ms
              quoted     2.000  i/100ms
     include col_sep     1.000  i/100ms
     include row_sep     1.000  i/100ms
        encode utf-8     3.000  i/100ms
         encode sjis     3.000  i/100ms
Calculating -------------------------------------
            unquoted     38.655  (± 5.2%) i/s -    195.000  in   5.054174s
              quoted     21.448  (± 4.7%) i/s -    108.000  in   5.041851s
     include col_sep     13.731  (± 0.0%) i/s -     69.000  in   5.030303s
     include row_sep      6.732  (± 0.0%) i/s -     34.000  in   5.056854s
        encode utf-8     31.144  (± 3.2%) i/s -    156.000  in   5.014613s
         encode sjis     33.007  (± 3.0%) i/s -    165.000  in   5.010195s
```