[enh] add MySQL engine

Slightly modified merge of [c00a33fe] from searx.

[c00a33fe] c00a33feee

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

searx/settings.yml

@@ -1225,6 +1225,16 @@ engines:
     # See : http://mymemory.translated.net/doc/usagelimits.php
     # api_key : ''
 
+# Required dependency: mysql-connector-python
+#  - name : mysql
+#    engine : mysql_server
+#    database : mydatabase
+#    username : user
+#    password : pass
+#    limit : 10
+#    query_str : 'SELECT * from mytable WHERE fieldname=%(query)s'
+#    shortcut : mysql
+
   - name : 1337x
     engine : 1337x
     shortcut : 1337x