message: Fixing package.json to accomodate npm v7
  1. We now require `prepublishOnly`
  2. env vars can only be found in "config" so the "sigma" key and vars were renamed
diff: "typings": "types/index.d.ts",
  "scripts": {
  "build": "webpack --progress && webpack --progress --mode production",
  - "clean": "rimraf $npm_package_sigma_clean",
  + "clean": "rimraf $npm_package_config_clean",
  "transpile": "tsc -p ./tsconfig.transpile.json -d --declarationDir types && replace '\\.glsl' '.glsl.js' renderers -r && webpack --config ./webpack.programs.config.js",
  "examples": "webpack serve --config ./examples/webpack.config.js --progress",
  "gitignore": "jq -r '.sigma.clean' package.json | tr ' ' '\\n' >> .gitignore",
  - "lint": "eslint $npm_package_sigma_folders --ext .ts",
  + "lint": "eslint $npm_package_config_folders --ext .ts",
  "postpublish": "npm run clean",
  - "prettier": "prettier --write $npm_package_sigma_folders",
  + "prettier": "prettier --write $npm_package_config_folders",
  "prepublish": "npm run lint && npm run test && npm run clean && npm run transpile && npm run build",
  + "prepublishOnly": "npm run prepublish",
  "test": "mocha --require ts-node/register ./test/unit/**/*.ts",
  "e2e:test": "mocha --require ts-node/register ./test/e2e/**/*.spec.ts --exit",
  "e2e:generate": "node -r ts-node/register test/e2e/generate.ts",
  "types": "npx tsc --declaration --emitDeclarationOnly --outDir lib"
  },
  - "sigma": {
  + "config": {
  "clean": "animate.js camera.js captor.js easings.js endpoint.js quadtree.js renderer.js type.js sigma-graphology.js utils.js captors heuristics renderers types",
  "folders": "examples src test"
  },
  