File view improvements

[ciyer]

Motivation

Working with the file view has made a few improvements clearer.

Proposal

Different modes as radio buttons

The current way of presenting the file-view modes is confusing, since you do not see which mode you are viewing.

This should be turned into a radio button.

The same for the menu above the file listing

Collapse file sidebar

I would like some kinds of files to take up the full width available. For this, we should support collapsing the file sidebar.

Context