The ? search operator has been broken for some time and
currently only raises the question why it's still there.
## Context ##
The query "Paris !images" searches for "Paris" in the "images" category.
Once upon a time Searx supported "Paris ?images" to search for "Paris"
in the currently enabled categories and the "images" category.
The feature makes sense ... the ? syntax does not.
We will hopefully introduce a +!images syntax in the future.
Fixes#702.
61935c72ef