chore: Rework ESLint config, format .prettierrc, add vendor stuff to …

….eslintignore

.eslintignore

@@ -1,3 +1,5 @@
 elm-stuff/
 template/
 tests/
+node_modules/
+build/

.eslintrc

@@ -0,0 +1,31 @@
+{
+  "env": {
+    "es6": true,
+    "node": true
+  },
+  "parserOptions": {
+    "ecmaVersion": 6
+  },
+  "extends": [
+    "eslint:recommended"
+  ],
+  "plugins": [
+    "prettier"
+  ],
+  "rules": {
+    "curly": "error",
+    "no-console": "off",
+    "no-else-return": "error",
+    "no-inner-declarations": "off",
+    "no-var": "error",
+    "prefer-arrow-callback": "error",
+    "prefer-const": "error",
+    "prettier/prettier": [
+      "error",
+      {
+        "singleQuote": true
+      }
+    ],
+    "strict": "error"
+  }
+}

.prettierrc

@@ -1,3 +1,3 @@
 {
-  singleQuote: true
+  "singleQuote": true
 }

tests/.eslintrc.js

@@ -0,0 +1,7 @@
+'use strict';
+
+module.exports = {
+  env: {
+    mocha: true
+  }
+};