Refactor File-list to become a view

[martinheidegger]

The file-list - in its current implementation - is problematic:

• It requires for a background process to keep up with all the files
• Each file (and status object) is kept in-memory and transferred to the list process
• The file-list is loaded even thought it is not rendered of all dat links!
• ... and put it in a redux state (in which they are redundant with the dat stored inside the dat)

(On top of that: The current implementation is buggy)

My suggestion is to turn the file-list into a DAT-view. Meaning: It becomes a view that has access to the DAT and and can iterate over it - without going to redux. As such it becomes the first implementation for #505 - the viewer architecture.