languages.py can change, so users may query on a language that is not
on the list anymore, even if it is still recognized by a few engines.

also made no and nb the same because they seem to return the same,
though most engines will only support one or the other.

closes issue #863

Fix #872. Google search works again with docker.

All the credit goes to Wonderfall. Thanks for that!
See: https://github.com/Wonderfall/dockerfiles/issues/110

fix #850

eliminate pagination bug in search forms

add library genesis engine

fix paging of duckduckgo

[mod] searx uses flask framework only in webapp.py

darker green for result url

[enh] make navbar smaller

[enh] make number of results less prominent

more compact results in Logicodev style

Input check

What has been moved into this template :
* opensearch*.xml is always the same whatever the themes.
* the text inside */about.html

Semantic Scholar

[enh] show spelling corrections

[WIP] Add 1337x.to engine