add total duration in 'hamster list' command

[madtibo]

Add a total time line at the bottom of the 'hamster list' command.

[ederag]

Thanks for your contribution.
It would be better to just sum deltas (that are timedelta),
and use stuff.format_duration for the display ?

[madtibo]

I saved the duration in seconds, is it better that way?

[ederag]

What about 4397d26 ?
Totals would use the same "human" format as in the duration column.

[madtibo]

Perfect!

[ederag]

Thanks for contributing !