v5.1.0-alpha.21

Features

• Addon-centered: Fix horizontal scrolling overflow (#6361)
• Angular: Support OnPush change detection for class-specified components (#6360)
• Addon-storysource: Reuase clientApi when possible (#6154)

Bug Fixes

• React-native: Fix backgrounds addon (#6393)
• UI: Fix 'read full changelog' link on about page (#6385)
• Addon-a11y: Fix addon initialization with 'makeDecorator' (#6354)
• Typescript: Fix a11y build by adding hoist-non-react-statics (#6348)

Maintenance

• Typescript: Use Babel instead of tsc (#5109)