i3: Rename workspaces with mod+n
i3: Make some specific windows/apps floating

* Thunar 'File Operation Progress' is made floating.
* Gpick (colour picker) window is made floating.
* Anything with a 'pop-up' window class is made floating.
bash: Add `hr` function to draw a line

$ hr
────────────────────────────────────────────────────────────────────────
$ hr '='
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