Clean up the architecture

Purposes :
- isolate the plugins calls
- distinction between parsing the web request and running the search (Search class). To be able to test code easily, to run searx code outside a web server, to filter the search query parameters with plugins more easily, etc...

Details :
- request.request_data contains request.form or request.args (initialize inside pre_request() function)
- Query class is renamed RawTextQuery
- SearchQuery class defines all search parameters
- get_search_query_from_webapp create a SearchQuery instance (basically the previous Search.__init__ code)
- Search class and SearchWithPlugins class takes a SearchQuery instance as class constructor parameter
- SearchWithPlugins class inherites from Search class, and run plugins
- A dedicated function search_with_plugins executes plugins to have a well define locals() (which is used by the plugins code).
- All plugins code is executed inside the try...except block (webapp.py, index function)
- advanced_search HTTP parameter value stays in webapp.py (it is only part of UI)
- multiple calls to result_container.get_ordered_results() doesn't compute the order multiple time (note : this method was call only once before)
- paging value is stored in the result_container class (compute in the extend method)
- test about engine.suspend_end_time is done during search method call (instead of __init__)
- check that the format parameter value is one of these : html, rss, json, rss (before the html value was assumed but some text formatting wasn't not done)

searx/plugins/self_info.py

@@ -37,10 +37,10 @@ def post_search(request, ctx):
             ip = x_forwarded_for[0]
         else:
             ip = request.remote_addr
-        ctx['search'].result_container.answers.clear()
-        ctx['search'].result_container.answers.add(ip)
+        ctx['result_container'].answers.clear()
+        ctx['result_container'].answers.add(ip)
     elif p.match(ctx['search'].query):
         ua = request.user_agent
-        ctx['search'].result_container.answers.clear()
-        ctx['search'].result_container.answers.add(ua)
+        ctx['result_container'].answers.clear()
+        ctx['result_container'].answers.add(ua)
     return True