Remove empty values from clickedIdStream

fixes #1098 on github

clickedIdStream represents the id of other features clicked from the mapFeature page map, allowing you to jump to that other feature's page. However, all clicks to the map were producing values in the stream, even ones that were not tied to an actual feature.

This fixes #1098 on github because the clicking of another feature tries to jump to a different page, which is blocked/prompted by the statePrompter during edit mode.
Add backend and templates for advanced search display filters
Fix ecobenefits searches for queries containing string parameters
Merge pull request #1198 from steventlamb/bug/1098_move_plot_confirmation

Remove empty values from clickedIdStream
Add support for display filters to search.js

 - Switched to ids in buildElems, since all search elements have ids now
   - This does require slightly changing things, to avoid breaking MIN/MAX
 - Added more tests
Merge pull request #1196 from maurizi/advanced-search-display-filters

Advanced search display filters
Add advanced search filter for trees missing photos