A couple of enhancements

Hi,

I've been using the app for some time, but I felt it lacks a couple of features.
They're all grouped together in this pull request:
- don't reload data too often
- upon refresh load stories as well as titles
- mark stories already read
- fullscreen mode for news reading mode (double tap to enter / leave)
- make scrolling faster (in news reading mode)

plus some smaller tweaks.

Cheers!