The engine name is not only a *name* its also a identifier that is used in
logs, HTTP headers and more. Unicode characters in the name of an engine could
cause various issues.
Closes: https://github.com/searxng/searxng/issues/1544
Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>
The general category is the category that is searched by default.
From a privacy standpoint it doesn't make sense to send all general
queries to specialized search engines that cannot deal with those
queries anyway.
