Star Content Improvement/Suggestions

[itbel]

Merging related issues

• Implement caching of previously downloaded JSONs for offline viewing.
• Implement the ability to partially bold text components
• Improvements to error handling.. pass error messages to the error screen. If the request times out in featured.json screen it would be good to add retry logic when screen is focused on navigate back.
• bottom tab nav animates nicely, it would be nice if header did this too. it is most visible when navigating from screens with hidden header, and back to screen with a header