Preserve filters (other than category) when changing categories.
Preserve filters (other than category) when changing categories.

 - also preserve filters when changing lot (other than category
   and lot!)

https://trello.com/c/kRvgV1GH/475-clicking-a-category-or-sub-category-wipes-out-the-filters

alphagov/digitalmarketplace-buyer-frontend,alphagov/digitalmarketplace-buyer-frontend,alphagov/digitalmarketplace-buyer-frontend,alphagov/digitalmarketplace-buyer-frontend