Rename exports, add benchmarking

[blakeembrey]

Rename the default export to a named export called create. I'm also planning to expose format in a future PR, similar to content-type, so that a ContentDisposition object can be round tripped (e.g. format(parse('')) should work).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.21%. Comparing base (4fbf7ff) to head (9789fc6).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #123      +/-   ##
==========================================
- Coverage   98.34%   98.21%   -0.14%     
==========================================
  Files           1        1              
  Lines         242      224      -18     
  Branches       87       82       -5     
==========================================
- Hits          238      220      -18     
  Misses          4        4              

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[Phillip9587]

LGTM