Time tracker for qutebrowser

[jgkamat]

It would be nice to have a general purpose time tracker in qutebrowser. Some ideas:

1. It could output to a simple, sorted plaintext files with <host> <time>
2. It could twiddle the indicator to show how "hot" a tab is
3. It could add an alternative to :buffer to sort buffers by their "hotness"
4. It could block domains after a certain time is used each day.

I'm not sure if there's a good 'time vizualizer' that can visualize files that we create (as it would be a waste of time to do it ourselves). Maybe we can generate a fake 'profile' that you could view in a flamechart viewer (where the TLD is the top level function which 'calls' subdomains).