since this is optimized for high-DPI screens (like tablets), use vector-based icons instead of raster icons
New UI

Improvements:
- Drag and drop
- Upload progress bars
- Page no longer flicks back to an old state when the network is laggy
- Page no longer piles multiple requests when the network is laggy
- Overwrite protection no longer depends on the directory list being
  current.

TODO:
- Control panel
- Delete buttons for files
new folder and delete buttons work