scratch 连接 block和vm 并运行
cd scratch-vm
npm install
npm link
npm run watch
cd ../scratch-blocks
npm install
npm link
cd ../scratch-gui
npm install
npm link scratch-vm scratch-blocks
npm start
cd scratch-vm
npm install
npm link
npm run watch
cd ../scratch-blocks
npm install
npm link
cd ../scratch-gui
npm install
npm link scratch-vm scratch-blocks
npm start