see searx.search.processors.abstract.EngineProcessor
First the method searx call the get_params method.
If the return value is not None, then the searx call the method search.
recoll is a local search engine based on Xapian:
http://www.lesbonscomptes.com/recoll/
By itself recoll does not offer web or API access,
this can be achieved using recoll-webui:
https://framagit.org/medoc92/recollwebui.git
This engine uses a custom 'files' result template
set `base_url` to the location where recoll-webui can be reached
set `dl_prefix` to a location where the file hierarchy as indexed by recoll can be reached
set `search_dir` to the part of the indexed file hierarchy to be searched, use an empty string to search the entire search domain
A new option is added to engines to hide error messages from users. It
is called `display_error_messages` and by default it is set to `True`.
If it is set to `False` error messages do not show up on the UI.
Keep in mind that engines are still suspended if needed regardless of
this setting.
Closes#1828
