[mod] split searx.search into different processors

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.

searx/engines/command.py

@@ -23,7 +23,7 @@ from threading import Thread
 from searx import logger
 
 
-offline = True
+engine_type = 'offline'
 paging = True
 command = []
 delimiter = {}