Release 1.2.0

• Change description (8a8b879)
• Add test for opts.level string (48e1490)
• Refactoring (890f3a7)
• Refactoring (e15173e)
• Refactoring (77f07b8)
• Fix code duplication (33ec770)
• Allow opts.level to be a string (5732b0d)
• Improve opts.level (ef8fc7d)
• Rename opts.getLevel() to opts.level() (315f2cd)
• Rename function (ca9d4b3)
• Rename opts.getMessage() to opts.message() (70a498d)
• Export main function top-level (208b056)
• Stop exposing constants (c84b9d1)
• Fix test (3907a56)
• Refactoring (0693e8b)
• Refactoring (85d7f4b)
• Always remove default Node.js listener for warning (dbf8c04)
• Remove @babel/register hack (a4cfcc2)
• Fix linting (4473b56)
• Fix support for Node.js 6|7 (47d614b)
• Fix console.debug() support in Node.js <8 (66bc90e)
• Fix tests under Node.js <8 (f92fb50)
• Fix Warnings test (5fcda98)
• Fix Node 9 support (e979291)
• Do not use process.off() (b52f1e5)
• Fix gulp audit (c8bbe58)
• Fix package-lock.json (018da38)
• Add support for Array.flatMap() (9509485)
• Fix line width (dd0214a)
• Support Node.js 6.5.0 (bba8804)
• Add testing for other Node.js versions (9790324)
• Fix linting (44c0044)
• Fix gulp files (b04d4d2)
• Remove docs directory (8746cb3)
• Remove yargs (662b58f)
• Use gulpfile.babel.js (112283f)
• Fix npm audit (6663616)
• Fix linting (2400424)
• Remove localpack (aaf03ae)
• Add gulp outdated (8be89c7)
• Upgrade lolex 3.0.0 -> 3.1.0 (d51b87a)
• Add gulp audit (3151e4b)
• Simplify eslintrc (55ae12b)
• Upgrade eslint-config-standard-prettier-fp 14.0.3 -> 15.0.0 (b801482)
• Upgrade eslint-plugin-eslint-comments 3.0.1 -> 3.1.0 (fc56633)