change: use float in flow_meter per-second

[mbarbin]

Allow Line.eta to display a duration for slow processes.

This experiments with @pveber proposal from #23, namely changing Flow_meter.per_second to return a float.

Note, the eta does not refresh as time passes, unlike Line.elapse, so possibly more changes are needed to improve further the display for slow processes (not done here).

I tested it with a slow process on my machine, and witnessed the display go from --:-- to an actual value after 2 reported updates.

[dinosaure]

It seems indeed a relevant pull-request. I will merge it and add it into the next release.

[mbarbin]

Hi @dinosaure Thanks for the recent release of 0.3.0 🚀 . Would you mind telling a few words regarding this PR, and the reason it wasn't included. What's holding it? I'm happy to have a fresh look. Thanks!

[dinosaure]

Hi @dinosaure Thanks for the recent release of 0.3.0 🚀 . Would you mind telling a few words regarding this PR, and the reason it wasn't included. What's holding it? I'm happy to have a fresh look. Thanks!

Hi @mbarbin, first, thanks for your work. I took a long time because I need to convince myself about the usage of a float instead of an Integer.t. As I said, I'm not particularly focused on performance and the use described by @pveber seems legitimate to me. I'm going to break the API (again), so it seems appropriate to integrate this PR from now on.