replace tslint with eslint + resolve linting issues

.eslintignore

@@ -0,0 +1,4 @@
+# compiled output
+/build
+/node_modules
+@types

.eslintrc.js

@@ -0,0 +1,12 @@
+module.exports = {
+  root: true,
+  parser: '@typescript-eslint/parser',
+  plugins: ['@typescript-eslint'],
+  env: {
+    node: true,
+  },
+  extends: ['eslint:recommended', 'plugin:@typescript-eslint/recommended', 'prettier'],
+  rules: {
+    '@typescript-eslint/no-unused-vars': ['warn', { argsIgnorePattern: '^_', ignoreRestSiblings: true }],
+  },
+};

.npmignore

@@ -15,7 +15,7 @@ npm-debug.log*
 tsconfig.json
 
 # Linter
-tslint.json
+.eslintrc.js
 
 # Testing and coverage
 test

.prettierrc

@@ -0,0 +1,8 @@
+{
+  "trailingComma": "all",
+  "tabWidth": 2,
+  "semi": true,
+  "singleQuote": true,
+  "bracketSpacing": true,
+  "printWidth": 120
+}