Work on app presentation (nice-to-have)

[vpmalley]

• [x] switch to previous/next item when swiping to right/left in the Feed Item Reader
• [x] add this thingy on the left of the action bar to display a side panel to navigate to today's/unread/downloaded/archived items
• [ ] make it possible for this navigation drawer to access weekly feeds/most popular author/most popular categories
• [ ] look at possibility to improve read/unread icon
• [x] offer possibility to switch between List and Grid for items
• [ ] Allow swiping a list item, if possible, to archive it or to add it to the starred list

[vpmalley]

Add access to downloaded podcasts