Remove a bunch of unused winnow code
Remove result_activate & result_deactivate functions

These are dom-based functions which add and remove classes to show
option availability. Our new options_build method makes them
unecessary.
Always set the result highlight after results are winnowed.

In this new version, the DOM is recreated every time the serach
filter changes. That means the element that @result_highlight refers
to is gone after a search.
Group results should be visible like any other search result.
Clear search results area if no results are found.
Rely on an option's search_match value instead of creating a
new variable to track match status. Also: change value to true if
a parts match is found.