5.20.0

• [browser] feat: Make @sentry/browser more treeshakeable (#2747)
• [browser] fix: Make sure that handler exists in LinkedErrors integration (#2742)
• [tracing] feat: Introduce @sentry/tracing (#2719)
• [tracing] ref: Use idleTimout if no activities occur in idle transaction (#2752)
• [react] feat: Export createReduxEnhancer to log redux actions as breadcrumbs, and attach state as an extra. (#2717)
• [react] feat: Add beforeCapture option to ErrorBoundary (#2753)
• [react] fix: Change import of hoist-non-react-statics (#2755)
• [gatsby] fix: Make @sentry/apm optional in @sentry/gatsby package (#2752)