[fix] Close #640 : remove MapQuest maps.

[fix] deviantart engine xpaths

Fix anomalous backslash in string

These lines were added to fix a js image load issue (#535) what i cannot reproduce.
Hopefully we don't see it again

Add Google Scholar search engine

utils/fetch_currencies: fix comment

Add ScanR structures search engine

[fix] multilingual duckduckgo

only works if both country and language are set

In theory ScanR should also search for projects but the API is different,
so we'd need another engine.

Comparison to None should be 'if cond is not None:'

Fix whitespaces

Fix quantity of blank lines after code object.

Add INA search engine

Remove trailing whitespace

use https instead of ssh with git-clone

Quote variables and backticks in manage.sh

Otherwise the script fails with spaces or asterisks in the directory path.

WARNING: dependency changes

remove unecessary capitalize of name of instance

The original code made by @logico-dev (#559)