message: Add fix:prettier npm script
diff: "pretest": "ts-node --transpile-only ./build_lualib.ts",
  "test": "jest",
  "lint": "npm run lint:tslint && npm run lint:prettier",
  - "lint:prettier": "prettier --check **/*.{js,ts,yml,json} || (echo 'Run `npm run lint:prettier -- --write` or `yarn lint:prettier --write` to fix it.' && exit 1)",
  + "lint:prettier": "prettier --check **/*.{js,ts,yml,json} || (echo 'Run `npm run fix:prettier` to fix it.' && exit 1)",
  "lint:tslint": "tslint -p . && tslint -p test && tslint src/lualib/*.ts",
  + "fix:prettier": "prettier --check --write **/*.{js,ts,yml,json}",
  "release-major": "npm version major",
  "release-minor": "npm version minor",
  "release-patch": "npm version patch",
  