4.3.1

• bumps to Typescript 3.4.2
• fixes Typescript build errors in external packages
• fixes compiler warnings
• fixes createBrowserHistory import
• adds @types/ws
• adds @types/graphql
• adds bufferutil
• bumps react-apollo -> 2.5.4
• bumps react-hot-loader -> 4.8.3
• adds utf-8-validate
• adds explicit incremental: true TS config option