Search results: prettier Location column

I noticed there were %20s and other URI junk in the Location field.

I think it would be much nicer to show relative paths from the search root folder if possible. If not, we should show the GIO parse name, which is basically an absolute local path, or a prettified absolute URL (see g_file_get_parse_name()

This merge does that. Hope it makes sense!

Test case: prettify-location-column.7z