Bug with duration filter

[cbeauchesne]

If you select more than one options with duration filter on routes, if they are not sorted, nothing is returned :

NOK : https://www.camptocamp.org/routes?act=skitouring&time=2,1
OK : https://www.camptocamp.org/routes?act=skitouring&time=1,2

[cbeauchesne]

It's because this filter is setted as a multiselect, it should be a slider defining a range.

time=a,b means [a,b], not {a,b}