Search: Save selected properties + link properties

[ScriptRaccoon]

This PR implements #130 and #131.

1. Selected properties on the search result page are links to their detail pages.
2. The selected properties are saved (in the browser's session storage). Thus, when the user goes back from the search result page to the search page*, they can adjust the search and do not need to start over. Hence, the button text "Start new search" has been replaced with "Adjust search"
3. On the search page, there is a button that clears the selected properties.
4. All adjustments to the category search have also been made to the functor search.

*Why these should be separate pages has been explained and implemented in #60.