🎨 style: Lint the code with xo.

Author: make-github-pseudonymous-again

package.json

@@ -94,7 +94,8 @@
     "np": "6.5.0",
     "nyc": "15.1.0",
     "power-assert": "1.6.1",
-    "regenerator-runtime": "0.13.7"
+    "regenerator-runtime": "0.13.7",
+    "xo": "^0.33.1"
   },
   "files": [
     "lib"
@@ -118,11 +119,27 @@
     "cover": "nyc --reporter=lcov npm test",
     "dev": "npm run lint -- --fix && npm run cover -- -- -st --fail-fast",
     "esdoc": "esdoc",
-    "lint": "true",
+    "lint": "xo",
     "prepare": "npm run build",
     "release": "np",
     "test": "ava",
     "travis": "npm run lint && npm run cover"
   },
-  "sideEffects": false
+  "sideEffects": false,
+  "xo": {
+    "prettier": true,
+    "ignore": [
+      "lib",
+      "doc"
+    ],
+    "rules": {
+      "camelcase": "off",
+      "unicorn/filename-case": [
+        "error",
+        {
+          "case": "camelCase"
+        }
+      ]
+    }
+  }
 }