Add option to translate duration

[SrBedrock]

Add a way to translate the name of the week, week, day and days.

The format for the duration is simple, first the weeks, then the days :

"1 week 2 days" means a total of 9 days
"2 weeks" means a total of 14 days
"3 day" means a total of 3 days
"12w 5d" means a total of 89 days (12*7 + 5)
"3d" means 3 days
and so on...

[EtienneDx]

I'll see what I can do for this