modernize tooling and resulting starter package

.eslintrc.json

@@ -0,0 +1,6 @@
+{
+  "extends": "@sourcegraph/eslint-config",
+  "parserOptions": {
+    "project": "tsconfig.json"
+  }
+}

.prettierignore

@@ -1,3 +1,2 @@
 package.json
-package-lock.json
 dist/

.travis.yml

@@ -1,24 +1,22 @@
 language: node_js
 node_js: '10'
-cache:
-  directories:
-    - ~/.npm
+cache: yarn
 env:
   global:
     - FORCE_COLOR=1
 install:
-  - npm ci
+  - yarn
 jobs:
   include:
     - stage: test
       script:
-        - npm run prettier
-        - npm run tslint
-        - npm run build
+        - yarn run prettier --write=false
+        - yarn run eslint
+        - yarn run build
     - stage: release
       script:
-        - npm run build
-        - npm run semantic-release
+        - yarn run build
+        - yarn run semantic-release
 stages:
   - test
   - name: release

.vscode/settings.json

@@ -1,3 +1,3 @@
 {
-  "typescript.tsdk": "node_modules/typescript/lib"
+  "typescript.tsdk": "node_modules/typescript/lib",
 }