Version 3.0.0

Changes:

• doctest now respects new opening-delimiter and closing-delimiter variables (#20)
• lint now runs eslint on .mjs files in addition to .js files (#17)
• test now runs nyc rather than running istanbul directly (#18)
• doctest dependency upgraded from 0.15.x to 0.16.x (#20)
• eslint dependency upgraded from 4.9.x to 5.15.x (#19)
• eslint-plugin-markdown dependency upgraded from 1.0.0-beta.8 to 1.0.x (#21)
• remark-cli dependency upgraded from 5.x.x to 6.x.x (#22)
• sanctuary-style dependency upgraded from 2.0.x to 3.0.x (#19)
• transcribe dependency upgraded from 1.1.1 to 1.1.2 (#23)